Divisibility Rules and Factors Worksheet
The method (Rules and powers): By 3 or 9: the digit sum divides by 3 or 9. By 4: the last two digits. By 8: the last three digits. By 6: even and divisible by 3. By 11: the sums of alternate digits are equal or differ by 11. Number of factors: write n = p^a × q^b …, then the count is (a + 1) × (b + 1) × …. To make n divisible by d: divide, then add (d − remainder) or take away the remainder.
NameDateTime takenScore ___ / 40
- 1.What is the smallest number you must take away from 608 so that it divides exactly by 13?
- 2.What is the smallest number you must add to 423 so that it divides exactly by 4?
- 3.What is the smallest number you must take away from 289 so that it divides exactly by 3?
- 4.What is the smallest number you must add to 213 so that it divides exactly by 13?
- 5.How many factors does 33 have?
- 6.What is the smallest number you must add to 177 so that it divides exactly by 11?
- 7.What is the smallest number you must take away from 394 so that it divides exactly by 7?
- 8.How many factors does 82 have?
- 9.How many factors does 81 have?
- 10.What is the smallest number you must add to 112 so that it divides exactly by 9?
- 11.How many factors does 55 have?
- 12.What is the smallest number you must add to 638 so that it divides exactly by 13?
- 13.What is the smallest number you must add to 416 so that it divides exactly by 9?
- 14.How many factors does 78 have?
- 15.Which of these numbers divides exactly by 9? (a) 7774 (b) 4642 (c) 6115 (d) 6453
- 16.What is the smallest number you must add to 197 so that it divides exactly by 4?
- 17.What is the smallest number you must add to 477 so that it divides exactly by 4?
- 18.Which of these numbers divides exactly by 9? (a) 9269 (b) 6318 (c) 7241 (d) 2852
- 19.What is the smallest number you must add to 338 so that it divides exactly by 7?
- 20.Which of these numbers divides exactly by 8? (a) 1988 (b) 2406 (c) 6688 (d) 7163
- 21.How many factors does 35 have?
- 22.Which of these numbers divides exactly by 6? (a) 8898 (b) 3531 (c) 9799 (d) 1853
- 23.What is the smallest number you must take away from 603 so that it divides exactly by 8?
- 24.How many factors does 12 have?
- 25.How many factors does 64 have?
- 26.Which of these numbers divides exactly by 11? (a) 1821 (b) 3733 (c) 8866 (d) 8713
- 27.What is the smallest number you must add to 301 so that it divides exactly by 13?
- 28.How many factors does 72 have?
- 29.What is the smallest number you must add to 996 so that it divides exactly by 8?
- 30.How many factors does 49 have?
- 31.Which of these numbers divides exactly by 8? (a) 5596 (b) 6802 (c) 8582 (d) 7056
- 32.What is the smallest number you must add to 119 so that it divides exactly by 9?
- 33.How many factors does 58 have?
- 34.What is the smallest number you must add to 571 so that it divides exactly by 4?
- 35.What is the smallest number you must take away from 981 so that it divides exactly by 11?
- 36.What is the smallest number you must take away from 471 so that it divides exactly by 9?
- 37.What is the smallest number you must add to 437 so that it divides exactly by 7?
- 38.How many factors does 71 have?
- 39.What is the smallest number you must take away from 331 so that it divides exactly by 7?
- 40.What is the smallest number you must take away from 347 so that it divides exactly by 8?
Answer key
- 10
- 1
- 1
- 8
- 4
- 10
- 2
- 4
- 5
- 5
- 4
- 12
- 7
- 8
- 6453
- 3
- 3
- 6318
- 5
- 6688
- 4
- 8898
- 3
- 6
- 7
- 8866
- 11
- 12
- 4
- 3
- 7056
- 7
- 4
- 1
- 2
- 3
- 4
- 2
- 2
- 3
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