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 22 have?
- 2.What is the smallest number you must add to 862 so that it divides exactly by 4?
- 3.What is the smallest number you must take away from 460 so that it divides exactly by 6?
- 4.How many factors does 17 have?
- 5.Which of these numbers divides exactly by 6? (a) 6161 (b) 1340 (c) 4416 (d) 1504
- 6.Which of these numbers divides exactly by 3? (a) 6124 (b) 1726 (c) 7758 (d) 5834
- 7.What is the smallest number you must add to 415 so that it divides exactly by 4?
- 8.Which of these numbers divides exactly by 11? (a) 4631 (b) 6835 (c) 3342 (d) 6178
- 9.What is the smallest number you must add to 427 so that it divides exactly by 12?
- 10.What is the smallest number you must take away from 815 so that it divides exactly by 12?
- 11.What is the smallest number you must take away from 709 so that it divides exactly by 11?
- 12.What is the smallest number you must take away from 415 so that it divides exactly by 7?
- 13.How many factors does 23 have?
- 14.Which of these numbers divides exactly by 9? (a) 3826 (b) 8222 (c) 5654 (d) 3618
- 15.What is the smallest number you must take away from 223 so that it divides exactly by 7?
- 16.What is the smallest number you must add to 335 so that it divides exactly by 3?
- 17.How many factors does 31 have?
- 18.How many factors does 91 have?
- 19.Which of these numbers divides exactly by 4? (a) 9191 (b) 9202 (c) 6961 (d) 9952
- 20.What is the smallest number you must add to 640 so that it divides exactly by 6?
- 21.Which of these numbers divides exactly by 8? (a) 3656 (b) 4255 (c) 9398 (d) 5572
- 22.Which of these numbers divides exactly by 9? (a) 3987 (b) 5443 (c) 3189 (d) 8027
- 23.Which of these numbers divides exactly by 6? (a) 3994 (b) 1141 (c) 7986 (d) 5099
- 24.What is the smallest number you must add to 955 so that it divides exactly by 7?
- 25.How many factors does 55 have?
- 26.What is the smallest number you must add to 954 so that it divides exactly by 12?
- 27.How many factors does 21 have?
- 28.What is the smallest number you must add to 859 so that it divides exactly by 3?
- 29.What is the smallest number you must add to 364 so that it divides exactly by 12?
- 30.What is the smallest number you must add to 191 so that it divides exactly by 4?
- 31.How many factors does 46 have?
- 32.What is the smallest number you must add to 582 so that it divides exactly by 12?
- 33.How many factors does 83 have?
- 34.How many factors does 51 have?
- 35.What is the smallest number you must add to 327 so that it divides exactly by 6?
- 36.What is the smallest number you must take away from 799 so that it divides exactly by 7?
- 37.What is the smallest number you must take away from 567 so that it divides exactly by 4?
- 38.What is the smallest number you must take away from 821 so that it divides exactly by 6?
- 39.What is the smallest number you must take away from 113 so that it divides exactly by 3?
- 40.What is the smallest number you must add to 496 so that it divides exactly by 3?
Answer key
- 4
- 2
- 4
- 2
- 4416
- 7758
- 1
- 4631
- 5
- 11
- 5
- 2
- 2
- 3618
- 6
- 1
- 2
- 4
- 9952
- 2
- 3656
- 3987
- 7986
- 4
- 4
- 6
- 4
- 2
- 8
- 1
- 4
- 6
- 2
- 4
- 3
- 1
- 3
- 5
- 2
- 2
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