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 353 so that it divides exactly by 12?
- 2.What is the smallest number you must add to 948 so that it divides exactly by 9?
- 3.What is the smallest number you must add to 985 so that it divides exactly by 8?
- 4.What is the smallest number you must add to 280 so that it divides exactly by 12?
- 5.Which of these numbers divides exactly by 4? (a) 7949 (b) 5361 (c) 8793 (d) 2720
- 6.What is the smallest number you must add to 502 so that it divides exactly by 13?
- 7.What is the smallest number you must add to 325 so that it divides exactly by 3?
- 8.How many factors does 63 have?
- 9.What is the smallest number you must add to 293 so that it divides exactly by 9?
- 10.Which of these numbers divides exactly by 6? (a) 1468 (b) 7592 (c) 3753 (d) 9480
- 11.Which of these numbers divides exactly by 6? (a) 9905 (b) 2032 (c) 6606 (d) 7378
- 12.How many factors does 93 have?
- 13.What is the smallest number you must add to 760 so that it divides exactly by 6?
- 14.How many factors does 50 have?
- 15.How many factors does 47 have?
- 16.What is the smallest number you must take away from 624 so that it divides exactly by 7?
- 17.How many factors does 58 have?
- 18.How many factors does 25 have?
- 19.What is the smallest number you must add to 838 so that it divides exactly by 11?
- 20.What is the smallest number you must take away from 271 so that it divides exactly by 4?
- 21.Which of these numbers divides exactly by 8? (a) 9257 (b) 1708 (c) 5874 (d) 6800
- 22.Which of these numbers divides exactly by 6? (a) 3172 (b) 8914 (c) 4800 (d) 9879
- 23.What is the smallest number you must take away from 310 so that it divides exactly by 8?
- 24.What is the smallest number you must take away from 108 so that it divides exactly by 11?
- 25.What is the smallest number you must take away from 156 so that it divides exactly by 7?
- 26.How many factors does 64 have?
- 27.How many factors does 16 have?
- 28.What is the smallest number you must add to 228 so that it divides exactly by 7?
- 29.What is the smallest number you must add to 847 so that it divides exactly by 13?
- 30.What is the smallest number you must add to 107 so that it divides exactly by 13?
- 31.Which of these numbers divides exactly by 9? (a) 3590 (b) 1560 (c) 1361 (d) 3699
- 32.Which of these numbers divides exactly by 8? (a) 2398 (b) 2840 (c) 5635 (d) 1345
- 33.What is the smallest number you must add to 722 so that it divides exactly by 11?
- 34.What is the smallest number you must add to 442 so that it divides exactly by 7?
- 35.What is the smallest number you must add to 579 so that it divides exactly by 13?
- 36.What is the smallest number you must add to 631 so that it divides exactly by 4?
- 37.What is the smallest number you must take away from 476 so that it divides exactly by 3?
- 38.What is the smallest number you must add to 840 so that it divides exactly by 9?
- 39.What is the smallest number you must add to 483 so that it divides exactly by 11?
- 40.What is the smallest number you must take away from 479 so that it divides exactly by 9?
Answer key
- 7
- 6
- 7
- 8
- 2720
- 5
- 2
- 6
- 4
- 9480
- 6606
- 4
- 2
- 6
- 2
- 1
- 4
- 3
- 9
- 3
- 6800
- 4800
- 6
- 9
- 2
- 7
- 5
- 3
- 11
- 10
- 3699
- 2840
- 4
- 6
- 6
- 1
- 2
- 6
- 1
- 2
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