BEATCALC:  Beat the Calculator!

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 Squaring Numbers

 Multiplying Numbers

  1. same 1st digit
  2. same 1st digit, sum 10
  3. same 2nd digit
  4. 3 digits, middle 0
  5. 3 digits, middle 1
  6. 3 digits, middle 2
  7. 3 digits, middle 3
  8. 3 digits, middle 4
  9. 3 digits, middle 5
  10. difference of 1
  11. difference of 2
  12. difference of 3
  13. difference of 4
  14. difference of 6
  15. difference of 8
  16. difference of 10
  17. 2 digits by 1 1/25
  18. 2 digits by 1 1/16
  19. 2 digits by 1.1
  20. 2 digits by 1 1/9
  21. 2 digits by 1 1/8
  22. 2 digits by 1 1/7
  23. 2 digits by 1 1/6
  24. 2 digits by 1 1/5
  25. 2 digits by 1 2/9
  26. 2 digits by 1 1/4
  27. 2 digits by 1 2/7
  28. 2 digits by 1.3
  29. 2 digits by 1 1/3
  30. 2 digits by 1 3/8
  31. 2 digits by 1 2/5
  32. 2 digits by 1 3/7
  33. 2 digits by 1 1/2
  34. 2 digits by 1 4/7
  35. 2 digits by 1 3/5
  36. 2 digits by 1.6
  37. 2,3 digits by 1 2/3
  38. 2 digits by 1.7
  39. 2 digits by 1 5/7
  40. 2 digits by 1 3/4
  41. 2 digits by 1 4/5
  42. 2 digits by 1 5/6
  43. 2 digits by 1 6/7
  44. 2 digits by 1.9
  45. 2 digits by 2.1
  46. 2 digits by 2 1/9
  47. 2 digits by 2 1/7
  48. 2 digits by 2 1/5
  49. 2 digits by 2 2/9
  50. 2 digits by 2 1/4
  51. 2 digits by 2.3
  52. 2 digits by 2 1/3
  53. 2 digits by 2 3/8
  54. 2 digits by 2 2/5
  55. 2 digits by 2.4
  56. 2 digits by 2 4/9
  57. 2, 3 digits by 2 1/2
  58. 2 digits by 2 4/7
  59. 2 digits by 2.6
  60. 2 digits by 2 5/8
  61. 2 digits by 2 2/3
  62. 2 digits by 2.7
  63. 2 digits by 2 5/7
  64. 2 digits by 2 3/4
  65. 2 digits by 2.8
  66. 2 digits by 2 7/9
  67. 2 digits by 2 6/7
  68. 2 digits by 2.9
  69. 2 digits by 3.1
  70. 2 digits by 3 1/8
  71. 2 digits by 3 1/7
  72. 2 digits by 3 1/6
  73. 2 digits by 3.2
  74. 2 digits by 3 2/9
  75. 2 digits by 3 1/4
  76. 2 digits by 3 1/3
  77. 2 digits by 3.4
  78. 2 digits by 3 3/7
  79. 2 digits by 3 4/9
  80. 2 digits by 3 1/2
  81. 2 digits by 3.6
  82. 2 digits by 3 4/7
  83. 2 digits by 3 5/8
  84. 2 digits by 3 2/3
  85. 2 digits by 3.7
  86. 2 digits by 3 5/7
  87. 2 digits by 3 3/4
  88. 2 digits by 3 4/5
  89. 2 digits by 3 6/7
  90. 2 digits by 3 7/8
  91. 2 digits by 3.9
  92. 2 digits by 4.1
  93. 2 digits by 4 1/4
  94. 2 digits by 4 1/7
  95. 2 digits by 4 1/6
  96. 2 digits by 4 1/5
  97. 2 digits by 4 2/7
  98. 2 digits by 4.3
  99. 2 digits by 4.4
  100. 2 digits by 4 3/7
  101. 2 digits by 4 4/9
  102. 2 digits by 4 1/2
  103. 2 digits by 4 5/9
  104. 2 digits by 4.6
  105. 2 digits by 4.7
  106. 2 digits by 4 3/4
  107. 2 digits by 4 4/5
  108. 2 digits by 4 5/6
  109. 2 digits by 4 7/8
  110. 2 digits by 4.9
  111. 2 digits by 5.1
  112. 2 digits by 5 1/8
  113. 2 digits by 5 1/6
  114. 2 digits by 5.2
  115. 2 digits by 5 1/4
  116. 2 digits by 5.3
  117. 2 digits by 5 4/9
  118. 2 digits by 5 1/2
  119. 2 digits by 5 5/9
  120. 2 digits by 5.6
  121. 2 digits by 5.7
  122. 2 digits by 5 4/7
  123. 2 digits by 5 5/7
  124. 2 digits by 5 4/5
  125. 2 digits by 5 6/7
  126. 2 digits by 5.9
  127. 2 digits by 6.1
  128. 2 digits by 6 1/8
  129. 2 digits by 6 1/5
  130. 2 digits by 6 1/4
  131. 2 digits by 6.3
  132. 2 digits by 6 1/3
  133. 2 digits by 6 3/8
  134. 2 digits by 6.4
  135. 2 digits by 6 4/9
  136. 2 digits by 6 1/2
  137. 2 digits by 6 5/9
  138. 2 digits by 6.6
  139. 2 digits by 6 2/3
  140. 2 digits by 6 7/9
  141. 2 digits by 6 5/6
  142. 2 digits by 6.8
  143. 2 digits by 6 6/7
  144. 2 digits by 6 8/9
  145. 2 digits by 7.1
  146. 2 digits by 7 1/7
  147. 2 digits by 7.2
  148. 2 digits by 7 1/4
  149. 2 digits by 7.3
  150. 2 digits by 7 2/7
  151. 2 digits by 7.4
  152. 2 digits by 7 1/2
  153. 2 digits by 7 3/5
  154. 2 digits by 7.6
  155. 2 digits by 7.7
  156. 2 digits by 7 3/4
  157. 2 digits by 7 4/5
  158. 2 digits by 8.1
  159. 2 digits by 8 1/6
  160. 2 digits by 8.2
  161. 2 digits by 8 2/7
  162. 2 digits by 8.3
  163. 2 digits by 8 1/3
  164. 2 digits by 8 3/7
  165. 2 digits by 8 4/7
  166. 2 digits by 8 1/2
  167. 2 digits by 8.6
  168. 2 digits by 8 5/8
  169. 2 digits by 8 2/3
  170. 2 digits by 8 5/7
  171. 2 digits by 8 7/9
  172. 2 digits by 8.8
  173. 2 digits by 8 7/8
  174. 2 digits by 8 8/9
  175. 2 digits by 9.1
  176. 2 digits by 9.2
  177. 2 digits by 9.3
  178. 2 digits by 9 1/3
  179. 2 digits by 9.4
  180. 2 digits by 9 1/2 (four steps)
  181. 2 digits by 9 1/2 (two steps)
  182. 2 digits by 9.6
  183. 2 digits by 9 2/3
  184. 2 digits by 9 5/7
  185. 2 digits by 9.7
  186. 2 digits by 9 3/4
  187. 2 digits by 9 7/9
  188. 2 digits by 9 4/5
  189. 2 digits by 9 5/6
  190. 2 digits by 9 6/7
  191. 2 digits by 9 7/8
  192. 2 digits by 9 8/9
  193. 2 digits by 10.1
  194. 2 digits by 10.4
  195. 2 digits by 10.6
  196. 2 digits by 10.7
  197. 2 digits by 10 1/2
  198. 2 digits by 11 1/2
  199. 2 digits by 12 1/2
  200. 2 digits by 15
  201. 2,3 digits by 16 2/3
  202. 2 digits by 18
  203. 2 digits by 19 1/2
  204. 2 digits by 20 1/2
  205. 2 digits by 21
  206. 2 digits by 22
  207. 2 digits by 23
  208. 2 digits by 24
  209. 2,3 digits by 25
  210. 2 digits by 26
  211. 2 digits by 27
  212. 2 digits by 28
  213. 2 digits by 29
  214. 2 digits by 29 1/2
  215. 2 digits by 30 1/2
  216. 2 digits by 31
  217. 2 digits by 32
  218. 2 digits by 33
  219. 2 digits by 33 1/3
  220. 2 digits by 34
  221. 2 digits by 35
  222. 2 digits by 36
  223. 2 digits by 37
  224. 2 digits by 37 1/2
  225. 2 digits by 38
  226. 2 digits by 39
  227. 2 digits by 39 1/2
  228. 2 digits by 40 1/2
  229. 2 digits by 42
  230. 2 digits by 43
  231. 2 digits by 44
  232. 2 digits by 45
  233. 2 digits by 46
  234. 2 digits by 47
  235. 2 digits by 48
  236. 2 digits by 49 (a)
  237. 2 digits by 49 (b)
  238. 2 digits by 49 1/2
  239. 2 digits by 50 1/2
  240. 2 digits by 51
  241. 2 digits by 52
  242. 2 digits by 53
  243. 2 digits by 54
  244. 2 digits by 55 (a)
  245. 2 digits by 55 (b)
  246. 2 digits by 56
  247. 2 digits by 57
  248. 2 digits by 58
  249. 2 digits by 59
  250. 2 digits by 59 1/2
  251. 2 digits by 60 1/2
  252. 2 digits by 61
  253. 2 digits by 62
  254. 2 digits by 63
  255. 2 digits by 64
  256. 2 digits by 65
  257. 2 digits by 66
  258. 2 digits by 67
  259. 2 digits by 68
  260. 2 digits by 69
  261. 2 digits by 69 1/2
  262. 2 digits by 70 1/2
  263. 2 digits by 71
  264. 2 digits by 72
  265. 2 digits by 73
  266. 2 digits by 74
  267. 2,3 digits by 75
  268. 2 digits by 76
  269. 2 digits by 77
  270. 2 digits by 78
  271. 2 digits by 79
  272. 2 digits by 79 1/2
  273. 2 digits by 80 1/2
  274. 2 digits by 81
  275. 2 digits by 82
  276. 2 digits by 83
  277. 2 digits by 84
  278. 2 digits by 85
  279. 2 digits by 86
  280. 2 digits by 87
  281. 2 digits by 88
  282. 2 digits by 89
  283. 2 digits by 89 1/2
  284. 2 digits by 90 1/2
  285. 2 digits by 91
  286. 2 digits by 92
  287. 2 digits by 93
  288. 2 digits by 94
  289. 2 digits by 97
  290. 2 digits by 98
  291. 2 digits by 99
  292. 3 digits by 99
  293. 2,3 digits by 101
  294. 2 digits by 102 + 11
  295. 2 digits by 103 + 12
  296. 2 digits by 125
  297. 3 digits by 143
  298. 2 digits by 166 2/3
  299. 2 digits by 198
  300. 2 digits by 201 + 11
  301. 2 digits by 202 + 11
  302. 2 digits by 250
  303. 2 digits by 297
  304. 2 digits by 375
  305. 2 digits by 396
  306. 2 digits by 495
  307. 2 digits by 594
  308. 2 digits by 625
  309. 2 digits by 693
  310. 2 digits by 792
  311. 2 digits by 875
  312. 2 digits by 891
  313. 2 digits by 999
  314. 2,3 digits by 1001 + 21,201
  315. 2-4 digits by 1000, + 21, 201, 2001
  316. 2-5 digits by 100001
  317. 1 rep. by 9 rep.
  318. 1 rep. by 12 rep.
  319. 1 rep. by 13 rep.
  320. 1 rep. by 14 rep.
  321. 1 rep. by 15 rep.
  322. 1 rep. by 16 rep.
  323. 1 rep. by 17 rep.
  324. 1 rep. by 18 rep.
  325. 1 rep. by 19 rep.
  326. 1 rep. by 21
  327. 1 rep. by 22
  328. 1 rep. by 23
  329. 1 rep. by 24
  330. 1 rep. by 25
  331. 1 rep. by 26
  332. 1 rep. by 27
  333. 1 rep. by 29
  334. 1 rep. by 33
  335. 1 rep. by 41
  336. 1 rep. by 44
  337. 1 rep. by 45
  338. 1 rep. by 55
  339. 1 rep. by 66
  340. 1 rep. by 77
  341. 1 rep. by 88
  342. 1 rep. by 99
  343. 1 rep. by 222
  344. 1 rep. by 333
  345. 2 rep. by 5 rep.
  346. 2 rep. by 9 rep.
  347. 2 rep. by 12
  348. 2 rep. by 13
  349. 2 rep. by 14
  350. 2 rep. by 15
  351. 2 rep. by 16
  352. 2 rep. by 17
  353. 2 rep. by 22
  354. 2 rep. by 24
  355. 2 rep. by 28
  356. 2 rep. by 33
  357. 2 rep. by 44
  358. 2 rep. by 45
  359. 2 rep. by 55
  360. 2 rep. by 66
  361. 2 rep. by 77
  362. 2 rep. by 88
  363. 2 rep. by 99
  364. 3 rep. by 6 rep.
  365. 3 rep. by 9 rep.
  366. 3 rep. by 13
  367. 3 rep. by 14
  368. 3 rep. by 15
  369. 3 rep. by 22
  370. 3 rep. by 23
  371. 3 rep. by 24
  372. 3 rep. by 35
  373. 3 rep. by 55
  374. 3 rep. by 66
  375. 3 rep. by 77
  376. 3 rep. by 88
  377. 3 rep. by 99
  378. 4 rep. by 15
  379. 4 rep. by 17
  380. 4 rep. by 22
  381. 4 rep. by 24
  382. 4 rep. by 28
  383. 4 rep. by 31
  384. 4 rep. by 36
  385. 4 rep. by 42
  386. 4 rep. by 44
  387. 4 rep. by 55
  388. 4 rep. by 66
  389. 4 rep. by 88
  390. 4 rep. by 99
  391. 4 rep. by 3 rep.
  392. 4 rep. by 5 rep.
  393. 4 rep. by 9 rep.
  394. 5 rep. by 15
  395. 5 rep. by 25
  396. 5 rep. by 28
  397. 5 rep. by 33
  398. 5 rep. by 55
  399. 5 rep. by 66
  400. 5 rep. by 77
  401. 5 rep. by 88
  402. 5 rep. by 9 rep.
  403. 6 rep. by 9 rep.
  404. 6 rep. by 12
  405. 6 rep. by 16
  406. 6 rep. by 22
  407. 6 rep. by 31
  408. 6 rep. by 32
  409. 6 rep. by 33
  410. 6 rep. by 43
  411. 6 rep. by 55
  412. 6 rep. by 66
  413. 6 rep. by 77
  414. 6 rep. by 88
  415. 6 rep. by 444
  416. 6 rep. by 888
  417. 7 rep. by 9 rep.
  418. 7 rep. by 17
  419. 7 rep. by 32
  420. 7 rep. by 33
  421. 7 rep. by 42
  422. 7 rep. by 44
  423. 7 rep. by 55
  424. 7 rep. by 66
  425. 7 rep. by 88
  426. 8 rep. by 9 rep.
  427. 8 rep. by 22
  428. 8 rep. by 23
  429. 8 rep. by 24
  430. 8 rep. by 29
  431. 8 rep. by 36
  432. 8 rep. by 44
  433. 8 rep. by 55
  434. 8 rep. by 66
  435. 8 rep. by 88
  436. 9 rep. by 14
  437. 9 rep. by 22
  438. 9 rep. by 25
  439. 9 rep. by 27
  440. 9 rep. by 33
  441. 9 rep. by 44
  442. 9 rep. by 55
  443. 9 rep. by 77
  444. 9 rep. by 99
  445. 3 repeating by 2, /37
  446. 3 repeating by 5, /37
  447. 9 rep. by 3, /12345679
  448. multi-digits by 8 + last digit
  449. by 8, add number, - 20
  450. integer + 1/2 times, + 1
  451. sum,difference of 2,1 digits
  452. two mixed numbers
  453. two mixed numbers,fractions
  454. 4 digits by 99
  455. 4 digits by 137, then 73; -1200
  456. 5 digits by 9091, then 11; -1200

 Dividing Numbers

 Adding Numbers

 Subtracting Numbers

 Finding Percents

Calculation
Practice Exercises

Full List


   Multiplying two 2-digit numbers
                (same 1st digit)

  1. Select two 2-digit numbers with the same first digit.
  2. Multiply their second digits (keep the carry).   _ _ _ X
  3. Multiply the sum of the second digits by the first digit,
    add the carry (keep the carry).   _ _ X _
  4. Multiply the first digits (add the carry).   X X _ _

   Example:

  1. If the first number is 42, choose 45 as the second number (any 2-digit number with first digit 4).
  2. Multiply the last digits: 2 × 5 = 10 (keep carry)  
    _ _ _ 0
  3. Multiply the sum of the 2nd digits by the first:
    5 + 2 = 7; 7 × 4 = 28; 28 + 1 = 29 (keep carry)  
    _ _ 9 _
  4. Multiply the first digits (add the carry)
    4 × 4 = 16; 16 + 2 = 18                           
    1 8 _ _

  5. So 42 × 45 = 1890.

   See the pattern?

  1. If the first number is 62, choose 67 as the second number
    (any 2-digit number with first digit 6).
  2. Multiply the last digits: 2 × 7 = 14 (keep carry)  
    _ _ _ 4
  3. Multiply the sum of the 2nd digits by the first (add carry):
    2 + 7 = 9; 6 × 9 = 54; 54 + 1 = 55 (keep carry)  
    _ _ 5 _
  4. Multiply the first digits (add the carry)
    6 × 6 = 36; 36 + 5 = 41                           
    4 1 _ _

  5. So 62 × 67 = 4154.


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3 November 1997
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