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 524 so that it divides exactly by 6?
- 2.What is the smallest number you must add to 544 so that it divides exactly by 7?
- 3.What is the smallest number you must add to 841 so that it divides exactly by 6?
- 4.How many factors does 93 have?
- 5.How many factors does 31 have?
- 6.How many factors does 66 have?
- 7.How many factors does 12 have?
- 8.How many factors does 51 have?
- 9.Which of these numbers divides exactly by 3? (a) 4684 (b) 9339 (c) 6424 (d) 2965
- 10.What is the smallest number you must take away from 690 so that it divides exactly by 11?
- 11.What is the smallest number you must take away from 101 so that it divides exactly by 3?
- 12.What is the smallest number you must take away from 373 so that it divides exactly by 8?
- 13.How many factors does 19 have?
- 14.How many factors does 50 have?
- 15.What is the smallest number you must add to 407 so that it divides exactly by 6?
- 16.How many factors does 20 have?
- 17.Which of these numbers divides exactly by 9? (a) 9172 (b) 9405 (c) 4924 (d) 1516
- 18.What is the smallest number you must add to 196 so that it divides exactly by 9?
- 19.What is the smallest number you must add to 287 so that it divides exactly by 12?
- 20.What is the smallest number you must add to 897 so that it divides exactly by 4?
- 21.Which of these numbers divides exactly by 9? (a) 3370 (b) 8626 (c) 1809 (d) 7476
- 22.What is the smallest number you must take away from 285 so that it divides exactly by 11?
- 23.How many factors does 32 have?
- 24.What is the smallest number you must add to 283 so that it divides exactly by 11?
- 25.What is the smallest number you must add to 850 so that it divides exactly by 7?
- 26.What is the smallest number you must add to 168 so that it divides exactly by 13?
- 27.What is the smallest number you must add to 690 so that it divides exactly by 7?
- 28.What is the smallest number you must add to 444 so that it divides exactly by 13?
- 29.What is the smallest number you must take away from 987 so that it divides exactly by 11?
- 30.What is the smallest number you must add to 487 so that it divides exactly by 8?
- 31.What is the smallest number you must take away from 149 so that it divides exactly by 3?
- 32.What is the smallest number you must take away from 305 so that it divides exactly by 3?
- 33.What is the smallest number you must add to 782 so that it divides exactly by 7?
- 34.Which of these numbers divides exactly by 9? (a) 2533 (b) 9588 (c) 1962 (d) 6437
- 35.What is the smallest number you must take away from 993 so that it divides exactly by 11?
- 36.Which of these numbers divides exactly by 11? (a) 1738 (b) 9785 (c) 7663 (d) 1156
- 37.What is the smallest number you must take away from 802 so that it divides exactly by 7?
- 38.How many factors does 99 have?
- 39.Which of these numbers divides exactly by 9? (a) 5928 (b) 6565 (c) 5582 (d) 4491
- 40.How many factors does 68 have?
Answer key
- 2
- 2
- 5
- 4
- 2
- 8
- 6
- 4
- 9339
- 8
- 2
- 5
- 2
- 6
- 1
- 6
- 9405
- 2
- 1
- 3
- 1809
- 10
- 6
- 3
- 4
- 1
- 3
- 11
- 8
- 1
- 2
- 2
- 2
- 1962
- 3
- 1738
- 4
- 6
- 4491
- 6
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