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 65 have?
- 2.What is the smallest number you must add to 358 so that it divides exactly by 12?
- 3.What is the smallest number you must add to 845 so that it divides exactly by 4?
- 4.What is the smallest number you must take away from 681 so that it divides exactly by 12?
- 5.How many factors does 32 have?
- 6.What is the smallest number you must take away from 116 so that it divides exactly by 8?
- 7.How many factors does 55 have?
- 8.How many factors does 79 have?
- 9.What is the smallest number you must add to 147 so that it divides exactly by 8?
- 10.What is the smallest number you must take away from 406 so that it divides exactly by 4?
- 11.How many factors does 41 have?
- 12.How many factors does 45 have?
- 13.Which of these numbers divides exactly by 3? (a) 7957 (b) 6461 (c) 4314 (d) 1897
- 14.Which of these numbers divides exactly by 4? (a) 7127 (b) 3763 (c) 8260 (d) 8625
- 15.How many factors does 82 have?
- 16.What is the smallest number you must add to 235 so that it divides exactly by 6?
- 17.How many factors does 61 have?
- 18.What is the smallest number you must take away from 473 so that it divides exactly by 6?
- 19.What is the smallest number you must add to 797 so that it divides exactly by 8?
- 20.What is the smallest number you must add to 308 so that it divides exactly by 6?
- 21.Which of these numbers divides exactly by 11? (a) 4081 (b) 2811 (c) 1139 (d) 6753
- 22.How many factors does 88 have?
- 23.Which of these numbers divides exactly by 9? (a) 1981 (b) 7400 (c) 4599 (d) 1871
- 24.What is the smallest number you must take away from 951 so that it divides exactly by 12?
- 25.What is the smallest number you must add to 995 so that it divides exactly by 9?
- 26.Which of these numbers divides exactly by 9? (a) 5880 (b) 6423 (c) 6606 (d) 8266
- 27.Which of these numbers divides exactly by 3? (a) 2459 (b) 5476 (c) 1920 (d) 6062
- 28.Which of these numbers divides exactly by 6? (a) 1096 (b) 9260 (c) 4638 (d) 3497
- 29.What is the smallest number you must add to 494 so that it divides exactly by 7?
- 30.What is the smallest number you must take away from 110 so that it divides exactly by 6?
- 31.How many factors does 42 have?
- 32.How many factors does 80 have?
- 33.How many factors does 53 have?
- 34.What is the smallest number you must take away from 274 so that it divides exactly by 3?
- 35.What is the smallest number you must take away from 151 so that it divides exactly by 12?
- 36.How many factors does 68 have?
- 37.How many factors does 44 have?
- 38.What is the smallest number you must take away from 991 so that it divides exactly by 9?
- 39.What is the smallest number you must take away from 686 so that it divides exactly by 9?
- 40.How many factors does 34 have?
Answer key
- 4
- 2
- 3
- 9
- 6
- 4
- 4
- 2
- 5
- 2
- 2
- 6
- 4314
- 8260
- 4
- 5
- 2
- 5
- 3
- 4
- 4081
- 8
- 4599
- 3
- 4
- 6606
- 1920
- 4638
- 3
- 2
- 8
- 10
- 2
- 1
- 7
- 6
- 6
- 1
- 2
- 4
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