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

 Dividing Numbers

 Adding Numbers

 Subtracting Numbers

 Finding Percents

Calculation
Practice Exercises

Full List


   Multiplying a 2-digit number by 1.9

  1. Select a 2-digit number.
  2. Multiply the number by 9.
  3. Move the decimal point one place left.
  4. Add this to the original number.

   Example:

  1. The 2-digit number chosen to multiply by 1.9 is 21.
  2. Multiply by 9: 9 × 21 = 189.
  3. Move decimal one place left: 18.9.
  4. Add original number: 18.9 + 21 = 39.9.
  5. So 1.9 × 21 = 39.9.

   See the pattern?

  1. The 2-digit number chosen to multiply by 1.9 is 33.
  2. Multiply by 9: 9 × 33 = 270 + 27 = 297.
  3. Move decimal on place left: 29.7.
  4. Add original number: 29.7 + 33 = 59.7 + 3 = 62.7.
  5. So 1.9 × 33 = 62.7.

Alternate method: Subtract .1 of original number (move decimal one place left) from 2 times original number. Try this method, too.

With some practice you will be able to give these products using one or both of these methods.


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24 August 2004
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