Divisibility Rules Everyone Should Know

Divisibility rules let you instantly check whether one number divides evenly into another — no long division required. These rules are essential for simplifying fractions, factoring, and competitive exams.

Divisible by 2

The number is even (ends in 0, 2, 4, 6, or 8). Example: 246 is divisible by 2.

Divisible by 3

The sum of the digits is divisible by 3. Example: 234 → 2+3+4 = 9, which is divisible by 3, so 234 is too.

Divisible by 4

The last two digits form a number divisible by 4. Example: 1,716 → 16 is divisible by 4, so 1,716 is too.

Divisible by 5

The number ends in 0 or 5. Example: 835 is divisible by 5.

Divisible by 6

The number is divisible by both 2 and 3. Example: 432 is even and 4+3+2=9 (divisible by 3), so 432 is divisible by 6.

Divisible by 7

Remove the last digit, double it, and subtract from the remaining number. Repeat if needed. Example: 343 → 34 − 2×3 = 28 → 2 − 2×8 = −14, which is divisible by 7.

Divisible by 8

The last three digits form a number divisible by 8. Example: 5,120 → 120 ÷ 8 = 15, so 5,120 is divisible by 8.

Divisible by 9

The sum of the digits is divisible by 9. Example: 8,154 → 8+1+5+4 = 18, divisible by 9.

Divisible by 10

The number ends in 0. Simple as that.

Divisible by 11

Subtract the sum of alternating digits. If the result is 0 or divisible by 11, the number is too. Example: 9,391 → (9+9) − (3+1) = 18 − 4 = 14, not divisible by 11. But 1,089 → (1+8) − (0+9) = 0, so 1,089 is divisible by 11.

Divisible by 12

The number is divisible by both 3 and 4. Example: 1,548 → digit sum 18 (divisible by 3) and 48 ÷ 4 = 12, so 1,548 is divisible by 12.

Practice these rules with the Math Champion division quiz — you will be surprised how much faster you get.