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 642 so that it divides exactly by 8?
- 2.What is the smallest number you must add to 189 so that it divides exactly by 13?
- 3.How many factors does 33 have?
- 4.What is the smallest number you must take away from 381 so that it divides exactly by 9?
- 5.How many factors does 90 have?
- 6.Which of these numbers divides exactly by 8? (a) 3079 (b) 7442 (c) 5349 (d) 9256
- 7.What is the smallest number you must add to 211 so that it divides exactly by 4?
- 8.What is the smallest number you must take away from 537 so that it divides exactly by 8?
- 9.What is the smallest number you must take away from 855 so that it divides exactly by 8?
- 10.How many factors does 49 have?
- 11.What is the smallest number you must add to 432 so that it divides exactly by 7?
- 12.Which of these numbers divides exactly by 3? (a) 6652 (b) 3335 (c) 2222 (d) 4779
- 13.How many factors does 80 have?
- 14.What is the smallest number you must add to 902 so that it divides exactly by 8?
- 15.What is the smallest number you must add to 509 so that it divides exactly by 3?
- 16.What is the smallest number you must take away from 667 so that it divides exactly by 3?
- 17.Which of these numbers divides exactly by 4? (a) 9750 (b) 5194 (c) 7632 (d) 5766
- 18.What is the smallest number you must add to 811 so that it divides exactly by 8?
- 19.How many factors does 32 have?
- 20.What is the smallest number you must add to 279 so that it divides exactly by 7?
- 21.How many factors does 21 have?
- 22.What is the smallest number you must add to 926 so that it divides exactly by 7?
- 23.How many factors does 75 have?
- 24.How many factors does 20 have?
- 25.How many factors does 42 have?
- 26.What is the smallest number you must add to 673 so that it divides exactly by 11?
- 27.Which of these numbers divides exactly by 6? (a) 5993 (b) 1765 (c) 2154 (d) 6322
- 28.What is the smallest number you must add to 646 so that it divides exactly by 6?
- 29.Which of these numbers divides exactly by 3? (a) 5505 (b) 7118 (c) 5038 (d) 7843
- 30.Which of these numbers divides exactly by 4? (a) 1154 (b) 2649 (c) 9316 (d) 3663
- 31.How many factors does 26 have?
- 32.What is the smallest number you must add to 371 so that it divides exactly by 13?
- 33.How many factors does 44 have?
- 34.What is the smallest number you must add to 452 so that it divides exactly by 8?
- 35.How many factors does 86 have?
- 36.What is the smallest number you must take away from 279 so that it divides exactly by 7?
- 37.What is the smallest number you must take away from 705 so that it divides exactly by 4?
- 38.What is the smallest number you must take away from 551 so that it divides exactly by 12?
- 39.Which of these numbers divides exactly by 6? (a) 5841 (b) 3749 (c) 7218 (d) 2607
- 40.Which of these numbers divides exactly by 6? (a) 8286 (b) 8433 (c) 2569 (d) 9921
Answer key
- 2
- 6
- 4
- 3
- 12
- 9256
- 1
- 1
- 7
- 3
- 2
- 4779
- 10
- 2
- 1
- 1
- 7632
- 5
- 6
- 1
- 4
- 5
- 6
- 6
- 8
- 9
- 2154
- 2
- 5505
- 9316
- 4
- 6
- 6
- 4
- 4
- 6
- 1
- 11
- 7218
- 8286
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