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 take away from 946 so that it divides exactly by 8?
- 2.How many factors does 72 have?
- 3.How many factors does 37 have?
- 4.What is the smallest number you must take away from 915 so that it divides exactly by 7?
- 5.Which of these numbers divides exactly by 8? (a) 5978 (b) 7961 (c) 5032 (d) 9150
- 6.How many factors does 25 have?
- 7.What is the smallest number you must add to 707 so that it divides exactly by 6?
- 8.How many factors does 69 have?
- 9.How many factors does 38 have?
- 10.Which of these numbers divides exactly by 4? (a) 7655 (b) 8276 (c) 1437 (d) 4910
- 11.Which of these numbers divides exactly by 3? (a) 2504 (b) 4709 (c) 8728 (d) 1545
- 12.How many factors does 12 have?
- 13.What is the smallest number you must take away from 160 so that it divides exactly by 3?
- 14.Which of these numbers divides exactly by 4? (a) 7490 (b) 6235 (c) 3152 (d) 5141
- 15.What is the smallest number you must take away from 425 so that it divides exactly by 3?
- 16.How many factors does 29 have?
- 17.How many factors does 75 have?
- 18.How many factors does 63 have?
- 19.What is the smallest number you must add to 783 so that it divides exactly by 8?
- 20.What is the smallest number you must add to 225 so that it divides exactly by 11?
- 21.What is the smallest number you must take away from 208 so that it divides exactly by 7?
- 22.Which of these numbers divides exactly by 3? (a) 9627 (b) 1118 (c) 8254 (d) 4411
- 23.How many factors does 39 have?
- 24.How many factors does 36 have?
- 25.Which of these numbers divides exactly by 8? (a) 9003 (b) 5200 (c) 1729 (d) 2442
- 26.How many factors does 28 have?
- 27.What is the smallest number you must take away from 651 so that it divides exactly by 4?
- 28.What is the smallest number you must take away from 386 so that it divides exactly by 6?
- 29.How many factors does 16 have?
- 30.What is the smallest number you must add to 437 so that it divides exactly by 13?
- 31.How many factors does 66 have?
- 32.What is the smallest number you must add to 856 so that it divides exactly by 9?
- 33.Which of these numbers divides exactly by 4? (a) 1942 (b) 8421 (c) 7120 (d) 1855
- 34.What is the smallest number you must add to 274 so that it divides exactly by 12?
- 35.Which of these numbers divides exactly by 3? (a) 6160 (b) 3751 (c) 8416 (d) 2244
- 36.What is the smallest number you must take away from 608 so that it divides exactly by 9?
- 37.What is the smallest number you must take away from 779 so that it divides exactly by 11?
- 38.What is the smallest number you must take away from 394 so that it divides exactly by 11?
- 39.How many factors does 95 have?
- 40.What is the smallest number you must take away from 985 so that it divides exactly by 4?
Answer key
- 2
- 12
- 2
- 5
- 5032
- 3
- 1
- 4
- 4
- 8276
- 1545
- 6
- 1
- 3152
- 2
- 2
- 6
- 6
- 1
- 6
- 5
- 9627
- 4
- 9
- 5200
- 6
- 3
- 2
- 5
- 5
- 8
- 8
- 7120
- 2
- 2244
- 5
- 9
- 9
- 4
- 1
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