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 31 have?
- 2.What is the smallest number you must add to 133 so that it divides exactly by 3?
- 3.What is the smallest number you must add to 997 so that it divides exactly by 7?
- 4.What is the smallest number you must add to 768 so that it divides exactly by 13?
- 5.How many factors does 46 have?
- 6.Which of these numbers divides exactly by 9? (a) 2411 (b) 8019 (c) 2822 (d) 8848
- 7.Which of these numbers divides exactly by 3? (a) 5216 (b) 5049 (c) 7712 (d) 2239
- 8.Which of these numbers divides exactly by 4? (a) 2315 (b) 3356 (c) 8038 (d) 5653
- 9.What is the smallest number you must take away from 946 so that it divides exactly by 13?
- 10.What is the smallest number you must take away from 604 so that it divides exactly by 3?
- 11.Which of these numbers divides exactly by 3? (a) 6551 (b) 6284 (c) 4102 (d) 9501
- 12.What is the smallest number you must take away from 485 so that it divides exactly by 6?
- 13.What is the smallest number you must take away from 194 so that it divides exactly by 3?
- 14.What is the smallest number you must add to 256 so that it divides exactly by 9?
- 15.What is the smallest number you must add to 947 so that it divides exactly by 6?
- 16.Which of these numbers divides exactly by 11? (a) 9436 (b) 9623 (c) 5060 (d) 5124
- 17.What is the smallest number you must take away from 898 so that it divides exactly by 13?
- 18.What is the smallest number you must add to 314 so that it divides exactly by 11?
- 19.How many factors does 20 have?
- 20.How many factors does 42 have?
- 21.How many factors does 83 have?
- 22.How many factors does 66 have?
- 23.What is the smallest number you must take away from 825 so that it divides exactly by 9?
- 24.What is the smallest number you must add to 569 so that it divides exactly by 13?
- 25.How many factors does 29 have?
- 26.Which of these numbers divides exactly by 3? (a) 4828 (b) 2302 (c) 7787 (d) 2247
- 27.How many factors does 65 have?
- 28.How many factors does 98 have?
- 29.What is the smallest number you must take away from 515 so that it divides exactly by 7?
- 30.Which of these numbers divides exactly by 9? (a) 1876 (b) 5163 (c) 9441 (d) 9944
- 31.How many factors does 21 have?
- 32.What is the smallest number you must take away from 241 so that it divides exactly by 7?
- 33.How many factors does 62 have?
- 34.What is the smallest number you must add to 490 so that it divides exactly by 9?
- 35.What is the smallest number you must take away from 118 so that it divides exactly by 3?
- 36.Which of these numbers divides exactly by 9? (a) 3442 (b) 1950 (c) 3346 (d) 2214
- 37.What is the smallest number you must add to 539 so that it divides exactly by 12?
- 38.Which of these numbers divides exactly by 11? (a) 8514 (b) 5480 (c) 3903 (d) 1645
- 39.What is the smallest number you must add to 313 so that it divides exactly by 4?
- 40.How many factors does 84 have?
Answer key
- 2
- 2
- 4
- 12
- 4
- 8019
- 5049
- 3356
- 10
- 1
- 9501
- 5
- 2
- 5
- 1
- 5060
- 1
- 5
- 6
- 8
- 2
- 8
- 6
- 3
- 2
- 2247
- 4
- 6
- 4
- 9441
- 4
- 3
- 4
- 5
- 1
- 2214
- 1
- 8514
- 3
- 12
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