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 531 so that it divides exactly by 12?
- 2.What is the smallest number you must add to 460 so that it divides exactly by 9?
- 3.What is the smallest number you must add to 348 so that it divides exactly by 7?
- 4.Which of these numbers divides exactly by 8? (a) 6635 (b) 9302 (c) 9087 (d) 9064
- 5.What is the smallest number you must take away from 547 so that it divides exactly by 3?
- 6.How many factors does 24 have?
- 7.How many factors does 21 have?
- 8.What is the smallest number you must take away from 379 so that it divides exactly by 11?
- 9.How many factors does 36 have?
- 10.How many factors does 22 have?
- 11.What is the smallest number you must take away from 320 so that it divides exactly by 13?
- 12.Which of these numbers divides exactly by 11? (a) 1397 (b) 4010 (c) 7076 (d) 5711
- 13.How many factors does 27 have?
- 14.How many factors does 82 have?
- 15.Which of these numbers divides exactly by 4? (a) 2566 (b) 4726 (c) 6120 (d) 4889
- 16.What is the smallest number you must take away from 932 so that it divides exactly by 6?
- 17.How many factors does 58 have?
- 18.What is the smallest number you must take away from 925 so that it divides exactly by 4?
- 19.How many factors does 18 have?
- 20.What is the smallest number you must take away from 117 so that it divides exactly by 6?
- 21.Which of these numbers divides exactly by 4? (a) 8105 (b) 2893 (c) 8033 (d) 1828
- 22.Which of these numbers divides exactly by 4? (a) 7188 (b) 3487 (c) 6875 (d) 4251
- 23.What is the smallest number you must take away from 523 so that it divides exactly by 3?
- 24.What is the smallest number you must take away from 991 so that it divides exactly by 6?
- 25.What is the smallest number you must take away from 155 so that it divides exactly by 7?
- 26.How many factors does 19 have?
- 27.How many factors does 46 have?
- 28.What is the smallest number you must take away from 202 so that it divides exactly by 4?
- 29.Which of these numbers divides exactly by 3? (a) 5473 (b) 7469 (c) 1541 (d) 3807
- 30.What is the smallest number you must add to 751 so that it divides exactly by 12?
- 31.What is the smallest number you must add to 165 so that it divides exactly by 12?
- 32.What is the smallest number you must take away from 507 so that it divides exactly by 8?
- 33.How many factors does 37 have?
- 34.What is the smallest number you must take away from 243 so that it divides exactly by 12?
- 35.Which of these numbers divides exactly by 11? (a) 9581 (b) 9842 (c) 4025 (d) 9967
- 36.Which of these numbers divides exactly by 6? (a) 2957 (b) 2746 (c) 1542 (d) 1331
- 37.What is the smallest number you must take away from 173 so that it divides exactly by 7?
- 38.What is the smallest number you must add to 768 so that it divides exactly by 11?
- 39.What is the smallest number you must take away from 263 so that it divides exactly by 3?
- 40.How many factors does 68 have?
Answer key
- 9
- 8
- 2
- 9064
- 1
- 8
- 4
- 5
- 9
- 4
- 8
- 1397
- 4
- 4
- 6120
- 2
- 4
- 1
- 6
- 3
- 1828
- 7188
- 1
- 1
- 1
- 2
- 4
- 2
- 3807
- 5
- 3
- 3
- 2
- 3
- 9581
- 1542
- 5
- 2
- 2
- 6
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