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 475 so that it divides exactly by 8?
- 2.How many factors does 47 have?
- 3.Which of these numbers divides exactly by 3? (a) 6230 (b) 9989 (c) 7476 (d) 1532
- 4.What is the smallest number you must add to 390 so that it divides exactly by 4?
- 5.What is the smallest number you must add to 269 so that it divides exactly by 3?
- 6.How many factors does 35 have?
- 7.What is the smallest number you must add to 544 so that it divides exactly by 11?
- 8.What is the smallest number you must take away from 383 so that it divides exactly by 8?
- 9.Which of these numbers divides exactly by 9? (a) 4158 (b) 5060 (c) 5900 (d) 1945
- 10.What is the smallest number you must take away from 990 so that it divides exactly by 12?
- 11.What is the smallest number you must take away from 774 so that it divides exactly by 8?
- 12.What is the smallest number you must add to 580 so that it divides exactly by 12?
- 13.How many factors does 73 have?
- 14.Which of these numbers divides exactly by 6? (a) 6768 (b) 4351 (c) 3549 (d) 3063
- 15.How many factors does 81 have?
- 16.How many factors does 99 have?
- 17.What is the smallest number you must take away from 999 so that it divides exactly by 13?
- 18.What is the smallest number you must take away from 806 so that it divides exactly by 6?
- 19.What is the smallest number you must add to 497 so that it divides exactly by 6?
- 20.How many factors does 39 have?
- 21.What is the smallest number you must add to 310 so that it divides exactly by 3?
- 22.What is the smallest number you must add to 137 so that it divides exactly by 4?
- 23.What is the smallest number you must add to 758 so that it divides exactly by 9?
- 24.Which of these numbers divides exactly by 4? (a) 9921 (b) 2420 (c) 1246 (d) 7986
- 25.What is the smallest number you must take away from 425 so that it divides exactly by 9?
- 26.How many factors does 33 have?
- 27.What is the smallest number you must add to 862 so that it divides exactly by 3?
- 28.How many factors does 43 have?
- 29.What is the smallest number you must add to 575 so that it divides exactly by 11?
- 30.How many factors does 46 have?
- 31.What is the smallest number you must add to 537 so that it divides exactly by 9?
- 32.Which of these numbers divides exactly by 8? (a) 6077 (b) 8424 (c) 6585 (d) 4533
- 33.How many factors does 38 have?
- 34.Which of these numbers divides exactly by 9? (a) 1206 (b) 9289 (c) 1447 (d) 1101
- 35.What is the smallest number you must take away from 835 so that it divides exactly by 3?
- 36.What is the smallest number you must take away from 883 so that it divides exactly by 6?
- 37.Which of these numbers divides exactly by 8? (a) 8332 (b) 7381 (c) 4592 (d) 4607
- 38.Which of these numbers divides exactly by 6? (a) 1295 (b) 1542 (c) 7034 (d) 4049
- 39.What is the smallest number you must take away from 256 so that it divides exactly by 12?
- 40.What is the smallest number you must take away from 856 so that it divides exactly by 6?
Answer key
- 5
- 2
- 7476
- 2
- 1
- 4
- 6
- 7
- 4158
- 6
- 6
- 8
- 2
- 6768
- 5
- 6
- 11
- 2
- 1
- 4
- 2
- 3
- 7
- 2420
- 2
- 4
- 2
- 2
- 8
- 4
- 3
- 8424
- 4
- 1206
- 1
- 1
- 4592
- 1542
- 4
- 4
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