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Math Main Page => Exercises - Math III
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Goal: to practise how to make use of distributive property on special numbers, like (A + B) * (A - B) = A*A - B*B, A*C +B*C = (A + B ) *C, A*C - B*C = (A-B) * C
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Friday July 30 2010
07:15:35 PM | Friday July 30 2010
07:15:35 PMFlip Answers |
| 1) | 201 * 199 = | | 1) 200 * 200 - 1 * 1 = 39999 |
| 2) | 390 * 410 = | | 2) 400 * 400 - 10 * 10 = 159900 |
| 3) | 204 * 196 = | | 3) 200 * 200 - 4 * 4 = 39984 |
| 4) | 405 * 395 = | | 4) 400 * 400 - 5 * 5 = 159975 |
| 5) | 97 * 103 = | | 5) 100 * 100 - 3 * 3 = 9991 |
| 6) | 293 * 307 = | | 6) 300 * 300 - 7 * 7 = 89951 |
| 7) | 305 * 295 = | | 7) 300 * 300 - 5 * 5 = 89975 |
| 8) | 402 * 398 = | | 8) 400 * 400 - 2 * 2 = 159996 |
| 9) | 102 * 98 = | | 9) 100 * 100 - 2 * 2 = 9996 |
| 10) | 97 * 103 = | | 10) 100 * 100 - 3 * 3 = 9991 |
| 11) | 60 * 95 + 40 * 95 = | | 11) ( 40 + 60) * 95 = 9500 |
| 12) | 85 * 256 - 56 * 85 = | | 12) ( 256 - 56) * 85 = 17000 |
| 13) | 86 * 47 + 53 * 86 = | | 13) ( 47 + 53) * 86 = 8600 |
| 14) | 240 * 43 - 43 * 40 = | | 14) ( 240 - 40) * 43 = 8600 |
| 15) | 69 * 73 + 31 * 73 = | | 15) ( 31 + 69) * 73 = 7300 |
| 16) | 259 * 91 - 59 * 91 = | | 16) ( 259 - 59) * 91 = 18200 |
| 17) | 159 * 46 - 59 * 46 = | | 17) ( 159 - 59) * 46 = 4600 |
| 18) | 245 * 58 - 45 * 58 = | | 18) ( 245 - 45) * 58 = 11600 |
| 19) | 94 * 263 - 63 * 94 = | | 19) ( 263 - 63) * 94 = 18800 |
| 20) | 94 * 66 + 134 * 94 = | | 20) ( 134 + 66) * 94 = 18800 |
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Score: ______________ | |
