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 19 have?
- 2.What is the smallest number you must add to 104 so that it divides exactly by 12?
- 3.How many factors does 96 have?
- 4.Which of these numbers divides exactly by 8? (a) 6644 (b) 6047 (c) 3248 (d) 9322
- 5.What is the smallest number you must take away from 498 so that it divides exactly by 9?
- 6.What is the smallest number you must add to 518 so that it divides exactly by 11?
- 7.What is the smallest number you must add to 595 so that it divides exactly by 6?
- 8.Which of these numbers divides exactly by 9? (a) 1840 (b) 3085 (c) 7298 (d) 7749
- 9.What is the smallest number you must add to 255 so that it divides exactly by 9?
- 10.What is the smallest number you must take away from 569 so that it divides exactly by 12?
- 11.Which of these numbers divides exactly by 3? (a) 9053 (b) 3343 (c) 2085 (d) 9689
- 12.How many factors does 31 have?
- 13.How many factors does 51 have?
- 14.What is the smallest number you must add to 307 so that it divides exactly by 6?
- 15.Which of these numbers divides exactly by 3? (a) 2920 (b) 6319 (c) 1086 (d) 2590
- 16.How many factors does 75 have?
- 17.What is the smallest number you must take away from 461 so that it divides exactly by 3?
- 18.How many factors does 38 have?
- 19.What is the smallest number you must take away from 124 so that it divides exactly by 11?
- 20.What is the smallest number you must take away from 295 so that it divides exactly by 4?
- 21.How many factors does 12 have?
- 22.How many factors does 76 have?
- 23.How many factors does 58 have?
- 24.Which of these numbers divides exactly by 6? (a) 2438 (b) 8590 (c) 7777 (d) 8118
- 25.How many factors does 78 have?
- 26.Which of these numbers divides exactly by 4? (a) 2570 (b) 5604 (c) 3141 (d) 9818
- 27.How many factors does 32 have?
- 28.How many factors does 24 have?
- 29.What is the smallest number you must add to 281 so that it divides exactly by 12?
- 30.Which of these numbers divides exactly by 4? (a) 7231 (b) 1469 (c) 2105 (d) 6368
- 31.Which of these numbers divides exactly by 11? (a) 3585 (b) 7189 (c) 1012 (d) 6879
- 32.What is the smallest number you must take away from 309 so that it divides exactly by 6?
- 33.How many factors does 28 have?
- 34.What is the smallest number you must add to 675 so that it divides exactly by 6?
- 35.What is the smallest number you must add to 825 so that it divides exactly by 12?
- 36.What is the smallest number you must take away from 612 so that it divides exactly by 13?
- 37.Which of these numbers divides exactly by 9? (a) 5842 (b) 1444 (c) 8096 (d) 4311
- 38.What is the smallest number you must take away from 619 so that it divides exactly by 3?
- 39.How many factors does 34 have?
- 40.What is the smallest number you must take away from 781 so that it divides exactly by 13?
Answer key
- 2
- 4
- 12
- 3248
- 3
- 10
- 5
- 7749
- 6
- 5
- 2085
- 2
- 4
- 5
- 1086
- 6
- 2
- 4
- 3
- 3
- 6
- 6
- 4
- 8118
- 8
- 5604
- 6
- 8
- 7
- 6368
- 1012
- 3
- 6
- 3
- 3
- 1
- 4311
- 1
- 4
- 1
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