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 17 have?
- 2.How many factors does 53 have?
- 3.What is the smallest number you must add to 984 so that it divides exactly by 7?
- 4.How many factors does 30 have?
- 5.How many factors does 67 have?
- 6.Which of these numbers divides exactly by 9? (a) 2460 (b) 1802 (c) 2363 (d) 5121
- 7.What is the smallest number you must add to 184 so that it divides exactly by 9?
- 8.Which of these numbers divides exactly by 6? (a) 8207 (b) 9215 (c) 3462 (d) 1171
- 9.Which of these numbers divides exactly by 6? (a) 8309 (b) 8912 (c) 7296 (d) 8167
- 10.How many factors does 84 have?
- 11.How many factors does 66 have?
- 12.How many factors does 73 have?
- 13.How many factors does 15 have?
- 14.How many factors does 13 have?
- 15.What is the smallest number you must take away from 380 so that it divides exactly by 13?
- 16.How many factors does 19 have?
- 17.What is the smallest number you must take away from 459 so that it divides exactly by 11?
- 18.What is the smallest number you must take away from 749 so that it divides exactly by 13?
- 19.What is the smallest number you must add to 974 so that it divides exactly by 7?
- 20.What is the smallest number you must add to 254 so that it divides exactly by 11?
- 21.What is the smallest number you must take away from 872 so that it divides exactly by 12?
- 22.How many factors does 16 have?
- 23.What is the smallest number you must add to 139 so that it divides exactly by 8?
- 24.What is the smallest number you must take away from 316 so that it divides exactly by 3?
- 25.What is the smallest number you must take away from 782 so that it divides exactly by 8?
- 26.Which of these numbers divides exactly by 11? (a) 2799 (b) 9767 (c) 7640 (d) 5643
- 27.What is the smallest number you must take away from 280 so that it divides exactly by 13?
- 28.What is the smallest number you must take away from 919 so that it divides exactly by 13?
- 29.What is the smallest number you must add to 933 so that it divides exactly by 6?
- 30.What is the smallest number you must add to 768 so that it divides exactly by 9?
- 31.How many factors does 31 have?
- 32.What is the smallest number you must add to 365 so that it divides exactly by 9?
- 33.What is the smallest number you must take away from 625 so that it divides exactly by 13?
- 34.What is the smallest number you must add to 555 so that it divides exactly by 9?
- 35.What is the smallest number you must add to 297 so that it divides exactly by 4?
- 36.What is the smallest number you must add to 425 so that it divides exactly by 9?
- 37.What is the smallest number you must take away from 254 so that it divides exactly by 11?
- 38.What is the smallest number you must add to 875 so that it divides exactly by 11?
- 39.What is the smallest number you must take away from 590 so that it divides exactly by 12?
- 40.What is the smallest number you must take away from 202 so that it divides exactly by 7?
Answer key
- 2
- 2
- 3
- 8
- 2
- 5121
- 5
- 3462
- 7296
- 12
- 8
- 2
- 4
- 2
- 3
- 2
- 8
- 8
- 6
- 10
- 8
- 5
- 5
- 1
- 6
- 5643
- 7
- 9
- 3
- 6
- 2
- 4
- 1
- 3
- 3
- 7
- 1
- 5
- 2
- 6
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