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 28 have?
- 2.What is the smallest number you must add to 534 so that it divides exactly by 9?
- 3.How many factors does 81 have?
- 4.What is the smallest number you must add to 960 so that it divides exactly by 7?
- 5.How many factors does 26 have?
- 6.What is the smallest number you must add to 676 so that it divides exactly by 8?
- 7.How many factors does 32 have?
- 8.Which of these numbers divides exactly by 9? (a) 8905 (b) 5006 (c) 6599 (d) 8874
- 9.What is the smallest number you must take away from 590 so that it divides exactly by 3?
- 10.What is the smallest number you must add to 353 so that it divides exactly by 13?
- 11.How many factors does 57 have?
- 12.What is the smallest number you must add to 969 so that it divides exactly by 7?
- 13.What is the smallest number you must add to 262 so that it divides exactly by 11?
- 14.Which of these numbers divides exactly by 9? (a) 1816 (b) 3664 (c) 2547 (d) 6502
- 15.What is the smallest number you must add to 301 so that it divides exactly by 3?
- 16.What is the smallest number you must take away from 773 so that it divides exactly by 13?
- 17.Which of these numbers divides exactly by 3? (a) 1445 (b) 5905 (c) 1743 (d) 4264
- 18.What is the smallest number you must add to 742 so that it divides exactly by 3?
- 19.Which of these numbers divides exactly by 3? (a) 4991 (b) 7541 (c) 6980 (d) 4404
- 20.What is the smallest number you must add to 912 so that it divides exactly by 11?
- 21.What is the smallest number you must take away from 964 so that it divides exactly by 11?
- 22.How many factors does 58 have?
- 23.Which of these numbers divides exactly by 4? (a) 9816 (b) 6625 (c) 2099 (d) 6558
- 24.How many factors does 36 have?
- 25.How many factors does 88 have?
- 26.How many factors does 20 have?
- 27.What is the smallest number you must take away from 778 so that it divides exactly by 7?
- 28.How many factors does 31 have?
- 29.What is the smallest number you must add to 824 so that it divides exactly by 13?
- 30.What is the smallest number you must take away from 273 so that it divides exactly by 6?
- 31.What is the smallest number you must take away from 311 so that it divides exactly by 9?
- 32.What is the smallest number you must take away from 740 so that it divides exactly by 8?
- 33.Which of these numbers divides exactly by 9? (a) 3963 (b) 3936 (c) 8478 (d) 1579
- 34.How many factors does 75 have?
- 35.How many factors does 43 have?
- 36.What is the smallest number you must take away from 734 so that it divides exactly by 13?
- 37.What is the smallest number you must take away from 216 so that it divides exactly by 11?
- 38.How many factors does 22 have?
- 39.Which of these numbers divides exactly by 3? (a) 2591 (b) 4336 (c) 2412 (d) 7592
- 40.What is the smallest number you must add to 109 so that it divides exactly by 8?
Answer key
- 6
- 6
- 5
- 6
- 4
- 4
- 6
- 8874
- 2
- 11
- 4
- 4
- 2
- 2547
- 2
- 6
- 1743
- 2
- 4404
- 1
- 7
- 4
- 9816
- 9
- 8
- 6
- 1
- 2
- 8
- 3
- 5
- 4
- 8478
- 6
- 2
- 6
- 7
- 4
- 2412
- 3
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