Math Main Page => Exercises - Math III
|
Goal: to practice 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
|
|
Wednesday September 09 2026
06:51:41 PM | Wednesday September 09 2026
06:51:41 PMFlip Answers |
| 1) | 405 * 395 = | | 1) 400 * 400 - 5 * 5 = 159975 |
| 2) | 310 * 290 = | | 2) 300 * 300 - 10 * 10 = 89900 |
| 3) | 97 * 103 = | | 3) 100 * 100 - 3 * 3 = 9991 |
| 4) | 391 * 409 = | | 4) 400 * 400 - 9 * 9 = 159919 |
| 5) | 408 * 392 = | | 5) 400 * 400 - 8 * 8 = 159936 |
| 6) | 210 * 190 = | | 6) 200 * 200 - 10 * 10 = 39900 |
| 7) | 299 * 301 = | | 7) 300 * 300 - 1 * 1 = 89999 |
| 8) | 296 * 304 = | | 8) 300 * 300 - 4 * 4 = 89984 |
| 9) | 210 * 190 = | | 9) 200 * 200 - 10 * 10 = 39900 |
| 10) | 99 * 101 = | | 10) 100 * 100 - 1 * 1 = 9999 |
| 11) | 61 * 45 + 45 * 39 = | | 11) ( 39 + 61) * 45 = 4500 |
| 12) | 66 * 57 + 66 * 43 = | | 12) ( 57 + 43) * 66 = 6600 |
| 13) | 63 * 69 + 131 * 63 = | | 13) ( 131 + 69) * 63 = 12600 |
| 14) | 87 * 158 - 87 * 58 = | | 14) ( 158 - 58) * 87 = 8700 |
| 15) | 65 * 46 + 54 * 65 = | | 15) ( 46 + 54) * 65 = 6500 |
| 16) | 143 * 44 - 43 * 44 = | | 16) ( 143 - 43) * 44 = 4400 |
| 17) | 44 * 41 + 44 * 59 = | | 17) ( 59 + 41) * 44 = 4400 |
| 18) | 58 * 42 + 42 * 42 = | | 18) ( 58 + 42) * 42 = 4200 |
| 19) | 159 * 73 + 41 * 73 = | | 19) ( 159 + 41) * 73 = 14600 |
| 20) | 90 * 258 - 90 * 58 = | | 20) ( 258 - 58) * 90 = 18000 |
|
Score: ______________ | |
