Some numbers divide evenly with no remainder — and there's a quick trick to check. Drag the slider and see which divisors fit instantly.
Try it: find a number divisible by every single divisor shown!
A divisibility rule is a quick trick to check if a number divides evenly by another, without doing the full division.
| Divisor | Rule |
|---|---|
| 2 | Last digit is 0, 2, 4, 6, or 8 |
| 3 | Sum of digits is divisible by 3 |
| 5 | Last digit is 0 or 5 |
| 9 | Sum of digits is divisible by 9 |
| 10 | Last digit is 0 |
Is 549 divisible by 3? Add the digits: 5+4+9 = 18. Since 18 is divisible by 3, 549 is divisible by 3
Find the common factors of 12 and 18. Factors of 12: 1,2,3,4,6,12. Factors of 18: 1,2,3,6,9,18. Common factors: 1, 2, 3, 6
Find the first two common multiples of 4 and 6. Multiples of 4: 4,8,12,16,20,24. Multiples of 6: 6,12,18,24. Common multiples: 12, 24
Two numbers are co-prime if their only common factor is 1 — their HCF is 1. Co-prime numbers don't have to be prime themselves.
Find the HCF of 48 and 18. Divide 48 by 18: remainder 12. Divide 18 by 12: remainder 6. Divide 12 by 6: remainder 0. HCF = 6
A shopkeeper has 36 pens and 60 pencils and wants to make identical gift bags with none left over. What is the greatest number of bags? Find HCF(36, 60) = 12 bags
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