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.How many factors does 84 have?
- 2.What is the smallest number you must take away from 961 so that it divides exactly by 13?
- 3.What is the smallest number you must take away from 526 so that it divides exactly by 11?
- 4.What is the smallest number you must take away from 601 so that it divides exactly by 4?
- 5.What is the smallest number you must add to 662 so that it divides exactly by 4?
- 6.How many factors does 70 have?
- 7.What is the smallest number you must add to 565 so that it divides exactly by 4?
- 8.How many factors does 98 have?
- 9.What is the smallest number you must take away from 459 so that it divides exactly by 6?
- 10.Which of these numbers divides exactly by 8? (a) 8015 (b) 8405 (c) 6488 (d) 6566
- 11.What is the smallest number you must take away from 508 so that it divides exactly by 12?
- 12.What is the smallest number you must add to 683 so that it divides exactly by 11?
- 13.Which of these numbers divides exactly by 3? (a) 9290 (b) 9645 (c) 1168 (d) 1843
- 14.What is the smallest number you must add to 489 so that it divides exactly by 13?
- 15.What is the smallest number you must take away from 117 so that it divides exactly by 4?
- 16.What is the smallest number you must take away from 311 so that it divides exactly by 3?
- 17.Which of these numbers divides exactly by 8? (a) 6665 (b) 1597 (c) 2301 (d) 1248
- 18.What is the smallest number you must add to 631 so that it divides exactly by 12?
- 19.What is the smallest number you must add to 838 so that it divides exactly by 3?
- 20.Which of these numbers divides exactly by 4? (a) 8361 (b) 4010 (c) 8609 (d) 7796
- 21.Which of these numbers divides exactly by 3? (a) 9305 (b) 1229 (c) 1148 (d) 6654
- 22.What is the smallest number you must take away from 912 so that it divides exactly by 9?
- 23.What is the smallest number you must add to 640 so that it divides exactly by 7?
- 24.What is the smallest number you must add to 224 so that it divides exactly by 3?
- 25.Which of these numbers divides exactly by 6? (a) 6173 (b) 4734 (c) 2023 (d) 9577
- 26.How many factors does 50 have?
- 27.How many factors does 14 have?
- 28.How many factors does 66 have?
- 29.How many factors does 100 have?
- 30.What is the smallest number you must add to 375 so that it divides exactly by 9?
- 31.What is the smallest number you must add to 812 so that it divides exactly by 3?
- 32.What is the smallest number you must add to 157 so that it divides exactly by 8?
- 33.Which of these numbers divides exactly by 11? (a) 5209 (b) 5721 (c) 6567 (d) 3489
- 34.What is the smallest number you must take away from 520 so that it divides exactly by 7?
- 35.What is the smallest number you must add to 299 so that it divides exactly by 11?
- 36.What is the smallest number you must take away from 173 so that it divides exactly by 12?
- 37.How many factors does 88 have?
- 38.Which of these numbers divides exactly by 11? (a) 7865 (b) 5651 (c) 2363 (d) 2419
- 39.What is the smallest number you must add to 457 so that it divides exactly by 4?
- 40.How many factors does 21 have?
Answer key
- 12
- 12
- 9
- 1
- 2
- 8
- 3
- 6
- 3
- 6488
- 4
- 10
- 9645
- 5
- 1
- 2
- 1248
- 5
- 2
- 7796
- 6654
- 3
- 4
- 1
- 4734
- 6
- 4
- 8
- 9
- 3
- 1
- 3
- 6567
- 2
- 9
- 5
- 8
- 7865
- 3
- 4
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