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 83 have?
- 2.What is the smallest number you must add to 686 so that it divides exactly by 8?
- 3.What is the smallest number you must add to 909 so that it divides exactly by 13?
- 4.Which of these numbers divides exactly by 8? (a) 8441 (b) 8053 (c) 2477 (d) 7224
- 5.How many factors does 25 have?
- 6.What is the smallest number you must take away from 387 so that it divides exactly by 11?
- 7.What is the smallest number you must add to 495 so that it divides exactly by 4?
- 8.How many factors does 49 have?
- 9.Which of these numbers divides exactly by 3? (a) 8071 (b) 1913 (c) 3939 (d) 6886
- 10.What is the smallest number you must take away from 479 so that it divides exactly by 4?
- 11.How many factors does 20 have?
- 12.Which of these numbers divides exactly by 6? (a) 2674 (b) 8607 (c) 7693 (d) 1344
- 13.What is the smallest number you must take away from 926 so that it divides exactly by 6?
- 14.What is the smallest number you must take away from 334 so that it divides exactly by 4?
- 15.What is the smallest number you must take away from 259 so that it divides exactly by 8?
- 16.How many factors does 84 have?
- 17.What is the smallest number you must add to 503 so that it divides exactly by 12?
- 18.Which of these numbers divides exactly by 3? (a) 3099 (b) 5243 (c) 2123 (d) 8258
- 19.How many factors does 29 have?
- 20.Which of these numbers divides exactly by 3? (a) 1811 (b) 3081 (c) 9508 (d) 2746
- 21.What is the smallest number you must take away from 667 so that it divides exactly by 3?
- 22.What is the smallest number you must add to 681 so that it divides exactly by 8?
- 23.How many factors does 45 have?
- 24.How many factors does 82 have?
- 25.What is the smallest number you must take away from 254 so that it divides exactly by 8?
- 26.Which of these numbers divides exactly by 4? (a) 4230 (b) 1305 (c) 1436 (d) 6530
- 27.What is the smallest number you must add to 801 so that it divides exactly by 4?
- 28.What is the smallest number you must add to 817 so that it divides exactly by 3?
- 29.Which of these numbers divides exactly by 8? (a) 3136 (b) 5165 (c) 7710 (d) 2899
- 30.What is the smallest number you must take away from 327 so that it divides exactly by 8?
- 31.Which of these numbers divides exactly by 6? (a) 9022 (b) 9057 (c) 8274 (d) 6710
- 32.What is the smallest number you must add to 195 so that it divides exactly by 12?
- 33.Which of these numbers divides exactly by 4? (a) 8493 (b) 2442 (c) 2516 (d) 7527
- 34.What is the smallest number you must take away from 179 so that it divides exactly by 13?
- 35.How many factors does 58 have?
- 36.How many factors does 94 have?
- 37.What is the smallest number you must add to 538 so that it divides exactly by 6?
- 38.What is the smallest number you must take away from 239 so that it divides exactly by 11?
- 39.How many factors does 33 have?
- 40.How many factors does 78 have?
Answer key
- 2
- 2
- 1
- 7224
- 3
- 2
- 1
- 3
- 3939
- 3
- 6
- 1344
- 2
- 2
- 3
- 12
- 1
- 3099
- 2
- 3081
- 1
- 7
- 6
- 4
- 6
- 1436
- 3
- 2
- 3136
- 7
- 8274
- 9
- 2516
- 10
- 4
- 4
- 2
- 8
- 4
- 8
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