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 23 have?
- 2.What is the smallest number you must add to 344 so that it divides exactly by 12?
- 3.What is the smallest number you must add to 450 so that it divides exactly by 7?
- 4.Which of these numbers divides exactly by 11? (a) 3290 (b) 9955 (c) 3991 (d) 4541
- 5.Which of these numbers divides exactly by 6? (a) 5448 (b) 1166 (c) 6226 (d) 3596
- 6.What is the smallest number you must take away from 305 so that it divides exactly by 3?
- 7.What is the smallest number you must take away from 859 so that it divides exactly by 6?
- 8.How many factors does 25 have?
- 9.Which of these numbers divides exactly by 11? (a) 9978 (b) 4154 (c) 6425 (d) 1936
- 10.How many factors does 45 have?
- 11.What is the smallest number you must add to 268 so that it divides exactly by 6?
- 12.What is the smallest number you must take away from 323 so that it divides exactly by 11?
- 13.Which of these numbers divides exactly by 9? (a) 2529 (b) 3487 (c) 8353 (d) 4173
- 14.What is the smallest number you must add to 445 so that it divides exactly by 9?
- 15.What is the smallest number you must take away from 686 so that it divides exactly by 9?
- 16.How many factors does 44 have?
- 17.How many factors does 18 have?
- 18.Which of these numbers divides exactly by 4? (a) 1286 (b) 4097 (c) 8348 (d) 7891
- 19.How many factors does 30 have?
- 20.How many factors does 99 have?
- 21.How many factors does 15 have?
- 22.How many factors does 92 have?
- 23.What is the smallest number you must add to 894 so that it divides exactly by 4?
- 24.What is the smallest number you must take away from 591 so that it divides exactly by 4?
- 25.What is the smallest number you must take away from 605 so that it divides exactly by 8?
- 26.What is the smallest number you must take away from 958 so that it divides exactly by 6?
- 27.Which of these numbers divides exactly by 9? (a) 1155 (b) 8280 (c) 6776 (d) 6789
- 28.What is the smallest number you must take away from 354 so that it divides exactly by 8?
- 29.What is the smallest number you must add to 306 so that it divides exactly by 7?
- 30.What is the smallest number you must add to 919 so that it divides exactly by 7?
- 31.How many factors does 64 have?
- 32.How many factors does 87 have?
- 33.What is the smallest number you must take away from 844 so that it divides exactly by 13?
- 34.How many factors does 62 have?
- 35.What is the smallest number you must take away from 479 so that it divides exactly by 3?
- 36.What is the smallest number you must take away from 270 so that it divides exactly by 11?
- 37.What is the smallest number you must add to 734 so that it divides exactly by 3?
- 38.What is the smallest number you must add to 293 so that it divides exactly by 13?
- 39.What is the smallest number you must add to 789 so that it divides exactly by 13?
- 40.What is the smallest number you must take away from 102 so that it divides exactly by 11?
Answer key
- 2
- 4
- 5
- 9955
- 5448
- 2
- 1
- 3
- 1936
- 6
- 2
- 4
- 2529
- 5
- 2
- 6
- 6
- 8348
- 8
- 6
- 4
- 6
- 2
- 3
- 5
- 4
- 8280
- 2
- 2
- 5
- 7
- 4
- 12
- 4
- 2
- 6
- 1
- 6
- 4
- 3
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