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 453 so that it divides exactly by 12?
- 2.What is the smallest number you must add to 284 so that it divides exactly by 8?
- 3.What is the smallest number you must add to 488 so that it divides exactly by 11?
- 4.Which of these numbers divides exactly by 8? (a) 9296 (b) 1670 (c) 1274 (d) 3954
- 5.How many factors does 79 have?
- 6.What is the smallest number you must take away from 811 so that it divides exactly by 13?
- 7.How many factors does 99 have?
- 8.What is the smallest number you must add to 577 so that it divides exactly by 6?
- 9.How many factors does 24 have?
- 10.What is the smallest number you must add to 249 so that it divides exactly by 4?
- 11.Which of these numbers divides exactly by 9? (a) 2406 (b) 5499 (c) 5979 (d) 7201
- 12.What is the smallest number you must take away from 507 so that it divides exactly by 6?
- 13.Which of these numbers divides exactly by 6? (a) 9386 (b) 4948 (c) 1609 (d) 3528
- 14.Which of these numbers divides exactly by 8? (a) 7126 (b) 6838 (c) 4010 (d) 9152
- 15.What is the smallest number you must add to 125 so that it divides exactly by 12?
- 16.What is the smallest number you must add to 639 so that it divides exactly by 12?
- 17.What is the smallest number you must add to 659 so that it divides exactly by 3?
- 18.Which of these numbers divides exactly by 3? (a) 8924 (b) 6497 (c) 3510 (d) 1840
- 19.How many factors does 16 have?
- 20.Which of these numbers divides exactly by 4? (a) 1121 (b) 2658 (c) 3052 (d) 7370
- 21.How many factors does 35 have?
- 22.How many factors does 56 have?
- 23.What is the smallest number you must add to 472 so that it divides exactly by 6?
- 24.Which of these numbers divides exactly by 3? (a) 7677 (b) 1534 (c) 8771 (d) 3620
- 25.What is the smallest number you must take away from 900 so that it divides exactly by 8?
- 26.What is the smallest number you must take away from 235 so that it divides exactly by 11?
- 27.What is the smallest number you must take away from 786 so that it divides exactly by 8?
- 28.How many factors does 18 have?
- 29.What is the smallest number you must take away from 764 so that it divides exactly by 13?
- 30.How many factors does 33 have?
- 31.What is the smallest number you must take away from 344 so that it divides exactly by 11?
- 32.What is the smallest number you must take away from 707 so that it divides exactly by 9?
- 33.How many factors does 75 have?
- 34.How many factors does 90 have?
- 35.How many factors does 46 have?
- 36.What is the smallest number you must take away from 124 so that it divides exactly by 3?
- 37.How many factors does 54 have?
- 38.What is the smallest number you must add to 445 so that it divides exactly by 12?
- 39.What is the smallest number you must take away from 963 so that it divides exactly by 4?
- 40.How many factors does 86 have?
Answer key
- 3
- 4
- 7
- 9296
- 2
- 5
- 6
- 5
- 8
- 3
- 5499
- 3
- 3528
- 9152
- 7
- 9
- 1
- 3510
- 5
- 3052
- 4
- 8
- 2
- 7677
- 4
- 4
- 2
- 6
- 10
- 4
- 3
- 5
- 6
- 12
- 4
- 1
- 8
- 11
- 3
- 4
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