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 add to 391 so that it divides exactly by 6?
- 2.How many factors does 56 have?
- 3.What is the smallest number you must take away from 393 so that it divides exactly by 7?
- 4.Which of these numbers divides exactly by 11? (a) 7831 (b) 5742 (c) 5776 (d) 6957
- 5.How many factors does 14 have?
- 6.What is the smallest number you must take away from 388 so that it divides exactly by 12?
- 7.Which of these numbers divides exactly by 8? (a) 6126 (b) 8637 (c) 3354 (d) 4896
- 8.What is the smallest number you must take away from 310 so that it divides exactly by 11?
- 9.What is the smallest number you must take away from 163 so that it divides exactly by 4?
- 10.What is the smallest number you must add to 568 so that it divides exactly by 6?
- 11.What is the smallest number you must take away from 616 so that it divides exactly by 12?
- 12.What is the smallest number you must take away from 193 so that it divides exactly by 3?
- 13.How many factors does 54 have?
- 14.Which of these numbers divides exactly by 9? (a) 4858 (b) 7791 (c) 2610 (d) 6436
- 15.What is the smallest number you must take away from 752 so that it divides exactly by 9?
- 16.How many factors does 31 have?
- 17.What is the smallest number you must take away from 385 so that it divides exactly by 3?
- 18.What is the smallest number you must take away from 163 so that it divides exactly by 3?
- 19.What is the smallest number you must take away from 355 so that it divides exactly by 6?
- 20.Which of these numbers divides exactly by 11? (a) 2940 (b) 2133 (c) 4948 (d) 8294
- 21.How many factors does 89 have?
- 22.What is the smallest number you must add to 303 so that it divides exactly by 4?
- 23.How many factors does 65 have?
- 24.Which of these numbers divides exactly by 3? (a) 2710 (b) 9685 (c) 8937 (d) 1753
- 25.Which of these numbers divides exactly by 4? (a) 8440 (b) 7553 (c) 2985 (d) 1569
- 26.What is the smallest number you must add to 987 so that it divides exactly by 8?
- 27.How many factors does 19 have?
- 28.How many factors does 92 have?
- 29.Which of these numbers divides exactly by 9? (a) 8089 (b) 2430 (c) 8610 (d) 5568
- 30.What is the smallest number you must take away from 262 so that it divides exactly by 7?
- 31.What is the smallest number you must take away from 569 so that it divides exactly by 7?
- 32.What is the smallest number you must take away from 346 so that it divides exactly by 4?
- 33.How many factors does 100 have?
- 34.What is the smallest number you must add to 730 so that it divides exactly by 3?
- 35.What is the smallest number you must take away from 865 so that it divides exactly by 4?
- 36.What is the smallest number you must take away from 799 so that it divides exactly by 9?
- 37.How many factors does 33 have?
- 38.How many factors does 42 have?
- 39.What is the smallest number you must take away from 631 so that it divides exactly by 13?
- 40.What is the smallest number you must add to 525 so that it divides exactly by 8?
Answer key
- 5
- 8
- 1
- 5742
- 4
- 4
- 4896
- 2
- 3
- 2
- 4
- 1
- 8
- 2610
- 5
- 2
- 1
- 1
- 1
- 8294
- 2
- 1
- 4
- 8937
- 8440
- 5
- 2
- 6
- 2430
- 3
- 2
- 2
- 9
- 2
- 1
- 7
- 4
- 8
- 7
- 3
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