the most tricky question?? do u 've d BRaIns to solve it?? hmmm

In a dark room which is completely closed with thick walls on all the sides and a hefty door. a bulb is kept inside for wich the switch is located on the outside of the room..
one can see whether d light is on or not only by opening the door and not by any other ways..

now u've got 3 switches on the switch board which is on the outer wall beside the door.

question: can u find out which one of the switch is the correct switch for the bulb

condition: u can open the door only once and that too when u ON only* one of the switch.
hmmmm.. smart enuff to answer me?? then do it....

u can request for the answer on my mail: bhargavcn@gmail.com
all the best gals n guys

Phone Book trick

Certainly, you can use the memory techniques from here to memorize the phone book, but why? How many times can you really show that?

This trick will imply that you’ve memorized the phone book.

Imagine this: You hand out 9 cards or slips of paper, each with a different digit from 1 to 9, and ask your spectator to mix them up. He is then to hand any 3 to one person, any of the remaining 3 to another person, and keep the remaining 3. With the help of the spectators, you generate a random equation, and ask the spectators to total it up. Once you’re given the total, you instantly recall a number in the local phone book ending with those digits!

How?

First, the mathematical part:

If you’re using a deck of cards, just get out the Ace through 9 of any suit. Otherwise, use slips of paper with 1 through 9 written on them.

They are mixed up by the spectators, and split among 3 people as described above.

You ask the spectator farthest to your left to choose any of their three digits, and call it out. You write it down as the hundreds digit of a number. You ask the person in the middle for any one of their numbers, and you write that down as the tens digit. Finally, you ask the rightmost spectator for any one of their numbers, and write that down as the ones digit of the first number.

As the numbers are given to you, you take them back, so they can’t call the same number twice.

The above process is repeated twice more, to generate two more 3-digit numbers. These three 3-digit numbers are then added up.

Let’s say person A wound up with cards 3, 4 and 6, spectator B wound up with cards 1, 7 and 8, and spectator C wound up with 2, 5 and 9. They might create the equation this way:

382
419
675 (total=1,476)

Or, the equation might wind up being:

472
615
389 (total=1,476)

…or some other arrangement.

It seems like this process could generate an impossible large amount of numbers. Actually, with the numbers 1 through 9 used to create three 3-digit numbers like this, you can only arrive at 198 different totals.

The only possible totals you can generate are the multiples of 9, ranging from 774 to 2,556 (every 9 multiple inbetween is possible).

If you’re comfortable linking and memorizing numbers, you need to create a list of phone numbers in the local phone book that end in 0774, 0783, 0792, and so on, up to 2556.

Using a reverse phone lookup utility on the internet, combined with the zip code and prefixes for the area, you can actually generate a list of suitable numbers and their associated names with minimal hassle. Don’t forget to make sure that each name is actually printed in the current edition of the phone book you’ll be using!

Once you have the list, you need to make the links from the numbers to the names. 198 links can be a challenge, so don’t try this if you’re just starting out in memory.

Obviously, this feat works better for big shows in larger metropolitan areas for which you have time to prepare with the local phone book.

The funny thing is that, while you’re actually doing an impressively large memory feat, you get credit for doing a memory feat on a far larger scale!

No, you won’t use this feat all the time. However, used at the right time and right place, you’ll leave a lasting impression!

the binary system made easy

Learning the Binary Code System couldn’t be easier with the system you are about to read.

Typically when trying to convert binary into numbers people refer to a chart of some sort to get their numbers. From now on you will be able to convert numbers into Binary and Binary into numbers within seconds.

What you need to learn is the Binary Code. Essentially all you need to do is memorize the numbers 1, 2, 4, 8, 16, 32, 64, 128, 256 etc… The pattern here is add the number to itself to get the next number. It’s that easy. 1 plus 1 is 2. 2 + 2 is four, 4 + 4 is 8 etc…

The Binary Code is a series of 1’s and 0’s (ones and zeros).
A binary number looks like this: 110011

Remember those numbers I should you? 1, 2, 4, 8, 16 etc?

When you are learning the binary code, all I ask you to do is write the numbers in reverse. So:

See how this is written? We start with 1, then 2, 4, 8, 16 etc and it is done right to left. This is important as it makes learning the Binary Number System a piece of cake.

Now what you need to do is image underneath the Binary Number System is putting either a 1 or a 0 (one or a zero) under each number, starting from the right to the left.

So if we were to put a 0 underneath the number 1 in the chart above, then a number 1 under number two above, then another 1 above number four we would have an image like this:

Where 1 1 0 is the Binary Number.

So how do we convert 110 into a number? Simple. Wherever there is a 1 add the numbers above it together. In this case add the 4 and 2 giving 6.

Therefore 110 in binary is 6 in decimal.

So how about doing this in reverse? What is 22 in binary? What we need to do is put a 1 underneath all the numbers that will allow us to add up to 22. We can’t use 32 as it is over 22. We can use 16 and the numbers below. But we need to use the numbers until they add up to 22.

So let’s try it.

16 + 8 = 24 so that brings us over 22 and we know then we can’t use 8 next.

16 + 4 = 20. Ok so we are nearly there. 20 + 2 = 22 great we reached out number. So with the Binary Number System just mark off underneath the numbers a 1 wherever we used the number. Where we didn’t use the number put a 0.

So we can now see that the number 22 in Binary is equal to 10110.

Bonus: Percentages

Bonus: Percentages

Yanni in comment 23 gave an excellent tip for working out percentages, so I have taken the liberty of duplicating it here:

Find 7 % of 300. Sound Difficult?

Percents: First of all you need to understand the word “Percent.” The first part is PER , as in 10 tricks per listverse page. PER = FOR EACH. The second part of the word is CENT, as in 100. Like Century = 100 years. 100 CENTS in 1 dollar… etc. Ok… so PERCENT = For Each 100.

So, it follows that 7 PERCENT of 100, is 7. (7 for each hundred, of only 1 hundred).
8 % of 100 = 8. 35.73% of 100 = 35.73
But how is that useful??

Back to the 7% of 300 question. 7% of the first hundred is 7. 7% of 2nd hundred is also 7, and yep, 7% of the 3rd hundred is also 7. So 7+7+7 = 21.

If 8 % of 100 is 8, it follows that 8% of 50 is half of 8 , or 4.

Break down every number that’s asked into questions of 100, if the number is less then 100, then move the decimal point accordingly.

EXAMPLES:
8%200 = ? 8 + 8 = 16.
8%250 = ? 8 + 8 + 4 = 20.
8%25 = 2.0 (Moving the decimal back).
15%300 = 15+15+15 =45.
15%350 = 15+15+15+7.5 = 52.5

Also it’s usefull to know that you can always flip percents, like 3% of 100 is the same as 100% of 3.

35% of 8 is the same as 8% of 35.

BEATCALC: Beat the Calculator!

From the BEATCALC mailing list:
a weekly service from B. Lee Clay, archived here by the Math Forum.
To subscribe to the BEATCALC mailing list, write to BEATCALC@aol.com.

Squaring Numbers

1. Squaring a 2-digit number beginning with 1
2. Squaring a 2-digit number beginning with 5
3. Squaring a 2-digit number beginning with 9
4. Squaring a 2-digit number ending in 1
5. Squaring a 2-digit number ending in 2
6. Squaring a 2-digit number ending in 3
7. Squaring a 2-digit number ending in 4
8. Squaring a 2-digit number ending in 5
9. Squaring a 2-digit number ending in 6
10. Squaring a 2-digit number ending in 7
11. Squaring a 2-digit number ending in 8
12. Squaring a 2-digit number ending in 9
13. Squaring numbers made up of ones
14. Squaring numbers made up of threes
15. Squaring numbers made up of sixes
16. Squaring numbers made up of nines
17. Squaring numbers in the twenties
18. Squaring numbers in the thirties
19. Squaring numbers in the forties
20. Squaring numbers in the fifties
21. Squaring numbers in the sixties
22. Squaring numbers in the seventies
23. Squaring numbers in the eighties
24. Squaring numbers in the hundreds
25. Squaring numbers in the two hundreds
26. Squaring numbers in the three hundreds
27. Squaring numbers in the four hundreds
28. Squaring numbers in the five hundreds
29. Squaring numbers in the six hundreds
30. Squaring numbers in the seven hundreds
31. Squaring numbers between 800 and 810
32. Squaring numbers in the nine hundreds
33. Squaring numbers between 1000 and 1100
34. Squaring numbers between 2000 and 2099
35. Squaring numbers between 3000 and 3099
36. Squaring numbers between 4000 and 4099
37. Squaring numbers between 5000 and 5099
38. Squaring numbers between 6000 and 6099
39. Squaring numbers between 7000 and 7099
40. Squaring special numbers (3's and final 1)
41. Squaring special numbers (3's and final 2)
42. Squaring special numbers (3's and final 4)
43. Squaring special numbers (3's and final 5)
44. Squaring special numbers (3's and final 6)
45. Squaring special numbers (3's and final 7)
46. Squaring special numbers (3's and final 8)
47. Squaring special numbers (3's and final 9)
48. Squaring special numbers (6's and final 1)
49. Squaring special numbers (6's and final 2)
50. Squaring special numbers (6's and final 3)
51. Squaring special numbers (6's and final 4)
52. Squaring special numbers (6's and final 5)
53. Squaring special numbers (6's and final 7)
54. Squaring special numbers (6's and final 8)
55. Squaring special numbers (6's and final 9)
56. Squaring special numbers (9's and final 1)
57. Squaring special numbers (9's and final 2)
58. Squaring special numbers (9's and final 3)
59. Squaring special numbers (9's and final 4)
60. Squaring special numbers (9's and final 5)
61. Squaring special numbers (9's and final 6)
62. Squaring special numbers (9's and final 7)
63. Squaring special numbers (9's and final 8)
64. Squaring special numbers (1 and repeating 3's)
65. Squaring special numbers (1 and repeating 6's)
66. Squaring special numbers (1 and repeating 9's)
67. Squaring special numbers (2 and repeating 3's)
68. Squaring special numbers (2 and repeating 6's)
69. Squaring special numbers (2 and repeating 9's)
70. Squaring special numbers (3 and repeating 6's)
71. Squaring special numbers (3 and repeating 9's)
72. Squaring special numbers (4 and repeating 3's)
73. Squaring special numbers (4 and repeating 6's)
74. Squaring special numbers (4 and repeating 9's)
75. Squaring special numbers (5 and repeating 3's)
76. Squaring special numbers (5 and repeating 6's)
77. Squaring special numbers (5 and repeating 9's)
78. Squaring special numbers (6 and repeating 3's)
79. Squaring special numbers (6 and repeating 9's)
80. Squaring special numbers (7 and repeating 3's)
81. Squaring special numbers (7 and repeating 6's)
82. Squaring special numbers (7 and repeating 9's)
83. Squaring special numbers (8 and repeating 3's)
84. Squaring special numbers (8 and repeating 9's)
85. Squaring special numbers (9 and repeating 3's)
86. Squaring special numbers (9 and repeating 6's)
87. Squaring a repeating 6-digit number
88. Squaring 2 rep. numbers, dividing by square of single digit

    Multiplying Numbers

89. Multiplying two selected 2-digit numbers (same 1st digit) [1]
90. Multiplying two selected 2-digit numbers (same 1st digit) [2]
91. Multiplying two selected 2-digit numbers (same 2nd digit)
92. Multiplying two selected 3-digit numbers (middle digit 0)
93. Multiplying two selected 3-digit numbers (middle digit 1)
94. Multiplying two selected 3-digit numbers (middle digit 2)
95. Multiplying two selected 3-digit numbers (middle digit 3)
96. Multiplying two selected 3-digit numbers (middle digit 4)
97. Multiplying two selected 3-digit numbers (middle digit 5)
98. Multiplying two 2-digit numbers with a difference of 1
99. Multiplying two 2-digit numbers with a difference of 2
100. Multiplying two 2-digit numbers with a difference of 3
101. Multiplying two 2-digit numbers with a difference of 4
102. Multiplying two 2-digit numbers with a difference of 6
103. Multiplying two 2-digit numbers with a difference of 8
104. Multiplying two 2-digit numbers with a difference of 10
105. Multiplying a 2-digit number by 1 1/25
106. Multiplying a 2-digit number by 1.1
107. Multiplying a 2-digit number by 1 1/9
108. Multiplying a 2-digit number by 1 1/8
109. Multiplying a 2-digit number by 1 1/7
110. Multiplying a 2-digit number by 1 1/6
111. Multiplying a 2-digit number by 1 1/5
112. Multiplying a 2-digit number by 1 2/9
113. Multiplying a 2-digit number by 1 1/4
114. Multiplying a 2-digit number by 1 2/7
115. Multiplying a 2-digit number by 1.3
116. Multiplying a 2-digit number by 1 1/3
117. Multiplying a 2-digit number by 1 3/8
118. Multiplying a 2-digit number by 1 2/5
119. Multiplying a 2-digit number by 1 3/7
120. Multiplying a 2-digit number by 1 1/2
121. Multiplying a 2-digit number by 1 4/7
122. Multiplying a 2-digit number by 1 3/5
123. Multiplying a 2-digit number by 1.6
124. Multiplying a 2- or 3-digit number by 1 2/3
125. Multiplying a 2-digit number by 1 5/7
126. Multiplying a 2-digit number by 1 3/4
127. Multiplying a 2-digit number by 1 4/5
128. Multiplying a 2-digit number by 1 5/6
129. Multiplying a 2-digit number by 1 6/7
130. Multiplying a 2-digit number by 1.9
131. Multiplying a 2-digit number by 2.1
132. Multiplying a 2-digit number by 2 1/9
133. Multiplying a 2-digit number by 2 1/7
134. Multiplying a 2-digit number by 2 1/5
135. Multiplying a 2-digit number by 2 2/9
136. Multiplying a 2-digit number by 2 1/4
137. Multiplying a 2-digit number by 2.3
138. Multiplying a 2-digit number by 2 1/3
139. Multiplying a 2-digit number by 2 3/8
140. Multiplying a 2-digit number by 2.4
141. Multiplying a 2-digit number by 2 2/5
142. Multiplying a 2-digit number by 2 4/9
143. Multiplying a 2- or 3-digit number by 2 1/2
144. Multiplying a 2-digit number by 2 4/7
145. Multiplying a 2-digit number by 2.6
146. Multiplying a 2-digit number by 2 5/8
147. Multiplying a 2-digit number by 2 2/3
148. Multiplying a 2-digit number by 2.7
149. Multiplying a 2-digit number by 2 5/7
150. Multiplying a 2-digit number by 2 3/4
151. Multiplying a 2-digit number by 2 7/9
152. Multiplying a 2-digit number by 2 6/7
153. Multiplying a 2-digit number by 2.9
154. Multiplying a 2-digit number by 3.1
155. Multiplying a 2-digit number by 3 1/8
156. Multiplying a 2-digit number by 3 1/7
157. Multiplying a 2-digit number by 3 1/6
158. Multiplying a 2-digit number by 3.2
159. Multiplying a 2-digit number by 3 2/9
160. Multiplying a 2-digit number by 3 1/3
161. Multiplying a 2-digit number by 3.4
162. Multiplying a 2-digit number by 3 3/7
163. Multiplying a 2-digit number by 3 4/9
164. Multiplying a 2-digit number by 3 1/2
165. Multiplying a 2-digit number by 3.6
166. Multiplying a 2-digit number by 3 4/7
167. Multiplying a 2-digit number by 3 5/8
168. Multiplying a 2-digit number by 3 2/3
169. Multiplying a 2-digit number by 3.7
170. Multiplying a 2-digit number by 3 5/7
171. Multiplying a 2-digit number by 3 3/4
172. Multiplying a 2-digit number by 3 4/5
173. Multiplying a 2-digit number by 3 6/7
174. Multiplying a 2-digit number by 3 7/8
175. Multiplying a 2-digit number by 3.9
176. Multiplying a 2-digit number by 4.1
177. Multiplying a 2-digit number by 4 1/4
178. Multiplying a 2-digit number by 4 1/7
179. Multiplying a 2-digit number by 4 1/6
180. Multiplying a 2-digit number by 4 1/5
181. Multiplying a 2-digit number by 4 2/7
182. Multiplying a 2-digit number by 4.3
183. Multiplying a 2-digit number by 4.4
184. Multiplying a 2-digit number by 4 3/7
185. Multiplying a 2-digit number by 4 4/9
186. Multiplying a 2-digit number by 4 1/2
187. Multiplying a 2-digit number by 4 5/9
188. Multiplying a 2-digit number by 4.6
189. Multiplying a 2-digit number by 4.7
190. Multiplying a 2-digit number by 4 3/4
191. Multiplying a 2-digit number by 4 4/5
192. Multiplying a 2-digit number by 4 5/6
193. Multiplying a 2-digit number by 4 7/8
194. Multiplying a 2-digit number by 5.1
195. Multiplying a 2-digit number by 5 1/8
196. Multiplying a 2-digit number by 5 1/6
197. Multiplying a 2-digit number by 5.2
198. Multiplying a 2-digit number by 5 1/4
199. Multiplying a 2-digit number by 5.3
200. Multiplying a 2-digit number by 5 4/9
201. Multiplying a 2-digit number by 5 1/2
202. Multiplying a 2-digit number by 5 5/9
203. Multiplying a 2-digit number by 5.6
204. Multiplying a 2-digit number by 5.7
205. Multiplying a 2-digit number by 5 4/7
206. Multiplying a 2-digit number by 5 5/7
207. Multiplying a 2-digit number by 5 4/5
208. Multiplying a 2-digit number by 5 6/7
209. Multiplying a 2-digit number by 5.9
210. Multiplying a 2-digit number by 6.1
211. Multiplying a 2-digit number by 6 1/8
212. Multiplying a 2-digit number by 6 1/5
213. Multiplying a 2-digit number by 6 1/4
214. Multiplying a 2-digit number by 6.3
215. Multiplying a 2-digit number by 6 1/3
216. Multiplying a 2-digit number by 6 3/8
217. Multiplying a 2-digit number by 6.4
218. Multiplying a 2-digit number by 6 4/9
219. Multiplying a 2-digit number by 6 1/2
220. Multiplying a 2-digit number by 6 5/9
221. Multiplying a 2-digit number by 6.6
222. Multiplying a 2-digit number by 6 2/3
223. Multiplying a 2-digit number by 6 7/9
224. Multiplying a 2-digit number by 6 5/6
225. Multiplying a 2-digit number by 6 6/7
226. Multiplying a 2-digit number by 6 8/9
227. Multiplying a 2-digit number by 7.1
228. Multiplying a 2-digit number by 7 1/7
229. Multiplying a 2-digit number by 7.2
230. Multiplying a 2-digit number by 7 1/4
231. Multiplying a 2-digit number by 7.3
232. Multiplying a 2-digit number by 7 2/7
233. Multiplying a 2-digit number by 7.4
234. Multiplying a 2-digit number by 7 1/2
235. Multiplying a 2-digit number by 7 3/5
236. Multiplying a 2-digit number by 7.6
237. Multiplying a 2-digit number by 7.7
238. Multiplying a 2-digit number by 7 3/4
239. Multiplying a 2-digit number by 7 4/5
240. Multiplying a 2-digit number by 8.1
241. Multiplying a 2-digit number by 8 1/6
242. Multiplying a 2-digit number by 8.2
243. Multiplying a 2-digit number by 8 2/7
244. Multiplying a 2-digit number by 8.3
245. Multiplying a 2-digit number by 8 1/3
246. Multiplying a 2-digit number by 8 3/7
247. Multiplying a 2-digit number by 8 4/7
248. Multiplying a 2-digit number by 8 1/2
249. Multiplying a 2-digit number by 8.6
250. Multiplying a 2-digit number by 8 5/8
251. Multiplying a 2-digit number by 8 2/3
252. Multiplying a 2-digit number by 8 5/7
253. Multiplying a 2-digit number by 8 7/9
254. Multiplying a 2-digit number by 8 7/8
255. Multiplying a 2-digit number by 8 8/9
256. Multiplying a 2-digit number by 9.1
257. Multiplying a 2-digit number by 9.2
258. Multiplying a 2-digit number by 9.3
259. Multiplying a 2-digit number by 9 1/3
260. Multiplying a 2-digit number by 9.4
261. Multiplying a 2-digit number by 9 1/2 (four steps)
262. Multiplying a 2-digit number by 9 1/2 (two steps)
263. Multiplying a 2-digit number by 9.6
264. Multiplying a 2-digit number by 9 2/3
265. Multiplying a 2-digit number by 9 5/7
266. Multiplying a 2-digit number by 9.7
267. Multiplying a 2-digit number by 9 3/4
268. Multiplying a 2-digit number by 9 7/9
269. Multiplying a 2-digit number by 9 4/5
270. Multiplying a 2-digit number by 9 5/6
271. Multiplying a 2-digit number by 9 6/7
272. Multiplying a 2-digit number by 9 7/8
273. Multiplying a 2-digit number by 9 8/9
274. Multiplying a 2-digit number by 10.1
275. Multiplying a 2-digit number by 10.4
276. Multiplying a 2-digit number by 10.7
277. Multiplying a 2-digit number by 10 1/2
278. Multiplying a 2-digit number by 11 1/2
279. Multiplying a 2-digit number by 12 1/2
280. Multiplying a 2-digit number by 15
281. Multiplying a 2- or 3-digit number by 16 2/3
282. Multiplying a 2-digit number by 18
283. Multiplying a 2-digit number by 19 1/2
284. Multiplying a 2-digit number by 20 1/2
285. Multiplying a 2-digit number by 21
286. Multiplying a 2-digit number by 22
287. Multiplying a 2-digit number by 23
288. Multiplying a 2-digit number by 24
289. Multiplying a 2- or 3-digit number by 25
290. Multiplying a 2-digit number by 26
291. Multiplying a 2-digit number by 27
292. Multiplying a 2-digit number by 28
293. Multiplying a 2-digit number by 29
294. Multiplying a 2-digit number by 29 ½
295. Multiplying a 2-digit number by 30 ½
296. Multiplying a 2-digit number by 31
297. Multiplying a 2-digit number by 32
298. Multiplying a 2-digit number by 33
299. Multiplying a 2-digit number by 33 1/3
300. Multiplying a 2-digit number by 34
301. Multiplying a 2-digit number by 35
302. Multiplying a 2-digit number by 36
303. Multiplying a 2-digit number by 37
304. Multiplying a 2-digit number by 37 1/2
305. Multiplying a 2-digit number by 38
306. Multiplying a 2-digit number by 39
307. Multiplying a 2-digit number by 39 1/2
308. Multiplying a 2-digit number by 40 1/2
309. Multiplying a 2-digit number by 42
310. Multiplying a 2-digit number by 43
311. Multiplying a 2-digit number by 44
312. Multiplying a 2-digit number by 45
313. Multiplying a 2-digit number by 46
314. Multiplying a 2-digit number by 47
315. Multiplying a 2-digit number by 48
316. Multiplying a 2-digit number by 49 (a)
317. Multiplying a 2-digit number by 49 (b)
318. Multiplying a 2-digit number by 49 1/2
319. Multiplying a 2-digit number by 50 1/2
320. Multiplying a 2-digit number by 51
321. Multiplying a 2-digit number by 52
322. Multiplying a 2-digit number by 53
323. Multiplying a 2-digit number by 54
324. Multiplying a 2-digit number by 55 (a)
325. Multiplying a 2-digit number by 55 (b)
326. Multiplying a 2-digit number by 56
327. Multiplying a 2-digit number by 57
328. Multiplying a 2-digit number by 58
329. Multiplying a 2-digit number by 59
330. Multiplying a 2-digit number by 59 1/2
331. Multiplying a 2-digit number by 60 1/2
332. Multiplying a 2-digit number by 61
333. Multiplying a 2-digit number by 62
334. Multiplying a 2-digit number by 63
335. Multiplying a 2-digit number by 64
336. Multiplying a 2-digit number by 65
337. Multiplying a 2-digit number by 66
338. Multiplying a 2-digit number by 67
339. Multiplying a 2-digit number by 68
340. Multiplying a 2-digit number by 69
341. Multiplying a 2-digit number by 69 1/2
342. Multiplying a 2-digit number by 70 1/2
343. Multiplying a 2-digit number by 71
344. Multiplying a 2-digit number by 72
345. Multiplying a 2-digit number by 73
346. Multiplying a 2- or 3-digit number by 75
347. Multiplying a 2-digit number by 76
348. Multiplying a 2-digit number by 77
349. Multiplying a 2-digit number by 78
350. Multiplying a 2-digit number by 79
351. Multiplying a 2-digit number by 79 1/2
352. Multiplying a 2-digit number by 80 1/2
353. Multiplying a 2-digit number by 81
354. Multiplying a 2-digit number by 82
355. Multiplying a 2-digit number by 83
356. Multiplying a 2-digit number by 84
357. Multiplying a 2-digit number by 85
358. Multiplying a 2-digit number by 86
359. Multiplying a 2-digit number by 87
360. Multiplying a 2-digit number by 88
361. Multiplying a 2-digit number by 89
362. Multiplying a 2-digit number by 89 1/2
363. Multiplying a 2-digit number by 90 1/2
364. Multiplying a 2-digit number by 91
365. Multiplying a 2-digit number by 92
366. Multiplying a 2-digit number by 93
367. Multiplying a 2-digit number by 94
368. Multiplying a 2-digit number by 97
369. Multiplying a 2-digit number by 99
370. Multiplying a 3-digit number by 99
371. Multiplying a 2- or 3-digit number by 101
372. Multiplying a 2-digit number by 102 and adding 11
373. Multiplying a 2-digit number by 103 and adding 12
374. Multiplying a 2-digit number by 125
375. Multiplying a 3-digit number by 143
376. Multiplying a 2-digit number by 166 2/3
377. Multiplying a 2-digit number by 198
378. Multiplying a 2-digit number by 201 and adding 11
379. Multiplying a 2-digit number by 202 and adding 11
380. Multiplying a 2-digit number by 250
381. Multiplying a 2-digit number by 297
382. Multiplying a 2-digit number by 375
383. Multiplying a 2-digit number by 396
384. Multiplying a 2-digit number by 495
385. Multiplying a 2-digit number by 594
386. Multiplying a 2-digit number by 625
387. Multiplying a 2-digit number by 693
388. Multiplying a 2-digit number by 792
389. Multiplying a 2-digit number by 875
390. Multiplying a 2-digit number by 891
391. Multiplying a 2-digit number by 999
392. Multiplying a 2- or 3-digit number by 1001 and adding 21 (or 201)
393. Multiplying a 2-, 3-, or 4-digit number by 10001 and adding 21, 201, or 2001
394. Multiplying a 2-, 3-, 4-, or 5-digit number by 100001
395. Multiplying repeating 1's by repeating 9's
396. Multiplying repeating 1's by 12
397. Multiplying repeating 1's by 14
398. Multiplying repeating 1's by 15
399. Multiplying repeating 1's by 16
400. Multiplying repeating 1's by 17
401. Multiplying repeating 1's by 18
402. Multiplying repeating 1's by 19
403. Multiplying repeating 1's by 21
404. Multiplying repeating 1's by 22
405. Multiplying repeating 1's by 24
406. Multiplying repeating 1's by 25
407. Multiplying repeating 1's by 26
408. Multiplying repeating 1's by 27
409. Multiplying repeating 1's by 29
410. Multiplying repeating 1's by 33
411. Multiplying repeating 1's by 41
412. Multiplying repeating 1's by 44
413. Multiplying repeating 1's by 45
414. Multiplying repeating 1's by 55
415. Multiplying repeating 1's by 66
416. Multiplying repeating 1's by 77
417. Multiplying repeating 1's by 88
418. Multiplying repeating 1's by 99
419. Multiplying repeating 1's by 222
420. Multiplying repeating 1's by 333
421. Multiplying repeating 2's by repeating 5's
422. Multiplying repeating 2's by repeating 9's
423. Multiplying repeating 2's by 12
424. Multiplying repeating 2's by 16
425. Multiplying repeating 2's by 17
426. Multiplying repeating 2's by 22
427. Multiplying repeating 2's by 28
428. Multiplying repeating 2's by 33
429. Multiplying repeating 2's by 44
430. Multiplying repeating 2's by 55
431. Multiplying repeating 2's by 66
432. Multiplying repeating 2's by 77
433. Multiplying repeating 2's by 88
434. Multiplying repeating 2's by 99
435. Multiplying repeating 3's by repeating 6's
436. Multiplying repeating 3's by repeating 9's
437. Multiplying repeating 3's by 13
438. Multiplying repeating 3's by 15
439. Multiplying repeating 3's by 23
440. Multiplying repeating 3's by 35
441. Multiplying repeating 3's by 55
442. Multiplying repeating 3's by 66
443. Multiplying repeating 3's by 77
444. Multiplying repeating 3's by 88
445. Multiplying repeating 3's by 99
446. Multiplying repeating 4's by 15
447. Multiplying repeating 4's by 17
448. Multiplying repeating 4's by 22
449. Multiplying repeating 4's by 24
450. Multiplying repeating 4's by 28
451. Multiplying repeating 4's by 31
452. Multiplying repeating 4's by 36
453. Multiplying repeating 4's by 42
454. Multiplying repeating 4's by 44
455. Multiplying repeating 4's by 55
456. Multiplying repeating 4's by 88
457. Multiplying repeating 4's by repeating 3's
458. Multiplying repeating 4's by repeating 5's
459. Multiplying repeating 4's by repeating 9's
460. Multiplying repeating 5's by 25
461. Multiplying repeating 5's by 28
462. Multiplying repeating 5's by 33
463. Multiplying repeating 5's by 45
464. Multiplying repeating 5's by 66
465. Multiplying repeating 5's by 88
466. Multiplying repeating 5's by repeating 9's
467. Multiplying repeating 6's by repeating 9's
468. Multiplying repeating 6's by 16
469. Multiplying repeating 6's by 12
470. Multiplying repeating 6's by 22
471. Multiplying repeating 6's by 31
472. Multiplying repeating 6's by 32
473. Multiplying repeating 6's by 33
474. Multiplying repeating 6's by 43
475. Multiplying repeating 6's by 66
476. Multiplying repeating 6's by 77
477. Multiplying repeating 6's by 88
478. Multiplying repeating 6's by 444
479. Multiplying repeating 6's by 888
480. Multiplying repeating 7's by repeating 9's
481. Multiplying repeating 7's by 17
482. Multiplying repeating 7's by 32
483. Multiplying repeating 7's by 33
484. Multiplying repeating 7's by 42
485. Multiplying repeating 7's by 44
486. Multiplying repeating 7's by 55
487. Multiplying repeating 7's by 88
488. Multiplying repeating 8's by repeating 9's
489. Multiplying repeating 8's by 22
490. Multiplying repeating 8's by 23
491. Multiplying repeating 8's by 29
492. Multiplying repeating 8's by 36
493. Multiplying repeating 8's by 44
494. Multiplying repeating 8's by 55
495. Multiplying repeating 8's by 66
496. Multiplying repeating 8's by 88
497. Multiplying repeating 9's by 14
498. Multiplying repeating 9's by 22
499. Multiplying repeating 9's by 25
500. Multiplying repeating 9's by 27
501. Multiplying repeating 9's by 33
502. Multiplying repeating 9's by 44
503. Multiplying repeating 9's by 55
504. Multiplying repeating 9's by 77
505. Multiplying repeating 9's by 99
506. Multiplying a repeating 3-digit number by 2, then dividing it by 37
507. Multiplying a repeating 3-digit number by 5, then dividing it by 37
508. Multiplying a repeating 9-digit number by 3, then dividing it by 12345679
509. Multiplying a multi-digit number by 8 and adding the last digit
510. Multiplying a number sequence by 8, adding a number, and subtracting 20
511. Multiply integer + 1/2 times the number +1
512. Multiplying the sum and the difference of a 2-digit and a 1-digit number
513. Multiplying two mixed numbers
514. Multiplying two mixed numbers with fractions adding to 1
515. Multiplying a 4-digit number by 99
516. Multiplying a 4-digit number by 137 and 73; subtracting 1200
517. Multiplying a 5-digit number by 9091 and 11; subtracting 1200

     Dividing Numbers

518. Dividing a number by 0.125
519. Dividing a 2-digit number by 1 1/9
520. Dividing a 2-digit number by 1 1/8
521. Dividing a 2-digit number by 1 1/7
522. Dividing a 2-digit number by 1 1/6
523. Dividing a 2-digit number by 1 1/5
524. Dividing a 2-digit number by 1 1/4
525. Dividing a 2-digit number by 1 2/7
526. Dividing a 2-digit number by 1 1/3
527. Dividing a 2-digit number by 1 2/5
528. Dividing a 2-digit number by 1 3/7
529. Dividing a 2-digit number by 1 1/2
530. Dividing a 2-digit number by 1 3/5
531. Dividing a 2-digit number by 1 2/3
532. Dividing a 2-digit number by 1 3/4
533. Dividing a 2-digit number by 1 4/5
534. Dividing a 2-digit number by 2 2/9
535. Dividing a 2-digit number by 2 1/4
536. Dividing a 2-digit number by 2 1/3
537. Dividing a 2- or 3-digit number by 2 1/2
538. Dividing a 2-digit number by 2 2/3
539. Dividing a 2-digit number by 2 6/7
540. Dividing a 2-digit number by 3 1/8
541. Dividing a 2- or 3-digit number by 3 1/3
542. Dividing a 2-digit number by 3 1/2
543. Dividing a 2-digit number by 3 4/7
544. Dividing a 2-digit number by 4 1/6
545. Dividing a 2-digit number by 4 2/7
546. Dividing a 2-digit number by 4 4/9
547. Dividing a 2-digit number by 4 1/2
548. Dividing a 2-digit number by 5 5/7
549. Dividing a 2-digit number by 6 1/4
550. Dividing a 2-digit number by 6 2/3
551. Dividing a 2-digit number by 7 1/7
552. Dividing a 2-digit number by 7 2/7
553. Dividing a 2-digit number by 7 1/2
554. Dividing a 2-digit number by 8 1/3
555. Dividing a 2-digit number by 8 4/7
556. Dividing a 2-digit number by 12 1/2
557. Dividing a 2-digit number by 15
558. Dividing a 2- or 3-digit number by 16 2/3
559. Dividing a 2- or 3-digit number by 25
560. Dividing a 2- or 3-digit number by 33 1/3
561. Dividing a 2- or 3-digit number by 35
562. Dividing a 2-digit number by 37 1/2
563. Dividing a 2-digit number by 40
564. Dividing a 2-digit number by 45
565. Dividing a 2-digit number by 50
566. Dividing a 2-digit number by 62 1/2
567. Dividing a 2- or 3-digit number by 66 2/3
568. Dividing a 2- or 3-digit number by 75
569. Dividing a 2-digit number by 83 1/3
570. Dividing a 2-digit number by 87 1/2
571. Dividing a 2-digit number by 125
572. Dividing a 2-digit number by 166 2/3
573. Dividing a 2-digit number by 250
574. Dividing a 2- or 3-digit number by 333 1/3
575. Dividing a 2-digit number by 375
576. Dividing a 2-digit number by 625
577. Dividing a 2-digit number by 875
578. Dividing a repeating 3-digit number by 37 and adding 41
579. Dividing a repeating 6-digit number by 15873
580. Dividing a repeating 6-digit number by 7, then by 13
581. Dividing a repeating 6-digit number by 13, then by 11
582. Dividing a repeating 6-digit number by 7, 11, and 13, then subtracting 101
583. Dividing a repeating 6-digit number by 37037, then multiplying by 5
584. Dividing mixed numbers by 2
585. Finding the difference of the squares of two consecutive 2-digit numbers
586. Finding the difference of the squares of two different 2-digit numbers
587. Finding the square root of squares of 2-digit numbers ending in 1
588. Finding the square root of a perfect square ending in 5

     Adding Numbers

589. Finding the sum of all even numbers from 2 through a selected 2-digit even number
590. Finding the sum of the digits of the square of repeating ones
591. Adding a sequence of consecutive odd numbers
592. Adding consecutive numbers between two numbers
593. Adding a sequence of numbers from one to a selected 2-digit number
594. Adding a sequence of numbers from one to a selected 1-digit number and back
595. Adding sequences of numbers in the 10's
596. Adding sequences of numbers in the 20's
597. Adding sequences of numbers in the 30's
598. Adding sequences of numbers in the 40's
599. Adding sequences of numbers in the 50's
600. Adding sequences of numbers in the 60's
601. Adding sequences of numbers in the 70's
602. Adding sequences of numbers in the 80's
603. Adding a series of doubles
604. Adding a series of quadruples
605. Adding a series of ten numbers

     Subtracting Numbers

606. Subtracting from a repeating 1's number, dividing by 9, subtracting 21
607. Subtracting from a repeating 8's number, dividing by 9, subtracting 10
608. Subtracting the squares of two numbers
609. Reversing/adding/subtracting 3-digit numbers

     Finding Percentages

610. Finding 2.5 percent of a number
611. Finding 5 percent of a number
612. Finding 15 percent of a number
613. Finding 20 percent of a number
614. Finding 25 percent of a number
615. Finding 33 1/3 percent of a number
616. Finding 40 percent of a number
617. Finding 45 percent of a number
618. Finding 55 percent of a number
619. Finding 70 percent of a number
620. Finding 75 percent of a number

     Calculation Practice Exercises

Find the Equation of a Line Given That You Know Two Points it Passes Through

http://www.webmath.com/equline1.html