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 28 have?
- 2.What is the smallest number you must add to 817 so that it divides exactly by 9?
- 3.How many factors does 27 have?
- 4.What is the smallest number you must take away from 263 so that it divides exactly by 6?
- 5.Which of these numbers divides exactly by 3? (a) 7712 (b) 8171 (c) 8382 (d) 8647
- 6.Which of these numbers divides exactly by 6? (a) 3156 (b) 6759 (c) 7227 (d) 4570
- 7.How many factors does 82 have?
- 8.What is the smallest number you must add to 523 so that it divides exactly by 7?
- 9.What is the smallest number you must take away from 544 so that it divides exactly by 3?
- 10.Which of these numbers divides exactly by 9? (a) 7712 (b) 8118 (c) 8628 (d) 2209
- 11.Which of these numbers divides exactly by 9? (a) 2547 (b) 2418 (c) 2119 (d) 8945
- 12.What is the smallest number you must add to 415 so that it divides exactly by 3?
- 13.What is the smallest number you must take away from 291 so that it divides exactly by 4?
- 14.What is the smallest number you must take away from 542 so that it divides exactly by 6?
- 15.Which of these numbers divides exactly by 6? (a) 3245 (b) 9043 (c) 4562 (d) 6978
- 16.What is the smallest number you must add to 831 so that it divides exactly by 8?
- 17.How many factors does 88 have?
- 18.What is the smallest number you must take away from 986 so that it divides exactly by 13?
- 19.How many factors does 13 have?
- 20.What is the smallest number you must add to 496 so that it divides exactly by 7?
- 21.How many factors does 23 have?
- 22.What is the smallest number you must add to 103 so that it divides exactly by 3?
- 23.How many factors does 97 have?
- 24.What is the smallest number you must add to 238 so that it divides exactly by 12?
- 25.What is the smallest number you must take away from 612 so that it divides exactly by 7?
- 26.Which of these numbers divides exactly by 8? (a) 7524 (b) 3671 (c) 5735 (d) 2312
- 27.How many factors does 92 have?
- 28.How many factors does 26 have?
- 29.How many factors does 32 have?
- 30.Which of these numbers divides exactly by 9? (a) 3868 (b) 5780 (c) 6339 (d) 9603
- 31.What is the smallest number you must take away from 812 so that it divides exactly by 3?
- 32.Which of these numbers divides exactly by 4? (a) 2209 (b) 2981 (c) 4136 (d) 5783
- 33.Which of these numbers divides exactly by 11? (a) 9149 (b) 9220 (c) 2354 (d) 3604
- 34.What is the smallest number you must take away from 109 so that it divides exactly by 9?
- 35.How many factors does 36 have?
- 36.How many factors does 58 have?
- 37.What is the smallest number you must add to 286 so that it divides exactly by 3?
- 38.How many factors does 47 have?
- 39.How many factors does 80 have?
- 40.How many factors does 78 have?
Answer key
- 6
- 2
- 4
- 5
- 8382
- 3156
- 4
- 2
- 1
- 8118
- 2547
- 2
- 3
- 2
- 6978
- 1
- 8
- 11
- 2
- 1
- 2
- 2
- 2
- 2
- 3
- 2312
- 6
- 4
- 6
- 9603
- 2
- 4136
- 2354
- 1
- 9
- 4
- 2
- 2
- 10
- 8
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