Is This Divisible By...?
Here are some simple ways to determine if a number is divisible by another number:
Divisible by 2
Is the number an even number? Then it is divisible by 2. Example: 500, 244, 568 are all divisible by 2.
Divisible by 3
Add up the sum of the number’s digits. If the sum is divisible by 3, then it is divisible by 3. Example: 64521 –> The sum of 6+4+5+2+1 is 18, which is divisible by 3. This, the original number 64521 is divisible by 3.
Divisible by 4
Look at the last two digits of the number. If the last two numbers are divisible by 4, so is the original number. Example: 612340 –> The last two digits 40 are divisible by 4, thus the number is divisible by 4.
Divisible by 5
Look at the last digit in the number. If this is divisible by 5 (ending in a 0 or 5), then it is divisible by 5. Example: 120 and 525 both end in either a 0 or 5, thus they are both divisible by 5.
Divisible by 6
If a number is divisible by 3 and 2 (above), it is divisible by 6. Example: 6480 –> This an even number (divisible by 2) AND the sum of its digits is 18, which is a multiple of 3 (divisible by 3). Thus it is also divisible by 6.
Divisible by 9
Similar to determining divisibility by 3, to determine divisibility by 9, add up the sum of the digits. If the sum is divisible by 9, so is the original number. Example: 5697 –> The sum of 5+6+9+7 = 27, which is divisible by 9. Thus the number 5697 is divisible by 9.
Divisible by 10
Does the number end in 0? Then it is divisible by 10. Example: 100, 25350, 1350, are all divisible by 10.
Divisible by 12
If the number is divisible by both 3 and 4 (rules above), then it also is by 12. Example: 7332 –> The sum of 7+3+3+2 = 15 (divisible by 3), and the last two digits 32 are divisible by 4. Thus, this number is also divisible by 12.
Follow these simple rules and be on your way to becoming a mathematics pro!