Divisibility Rules 2–20
Practical tests for checking divisibility without performing full division.
| Divisor | Quick test | Example |
|---|---|---|
| 2 | Last digit is even: 0, 2, 4, 6, 8 | 438 → yes |
| 3 | Sum of digits is divisible by 3 | 372: 3+7+2=12 → yes |
| 4 | Last two digits are divisible by 4 | 1,316: 16 → yes |
| 5 | Last digit is 0 or 5 | 7,845 → yes |
| 6 | Divisible by both 2 and 3 | 534 → yes |
| 7 | Double last digit and subtract from remaining number; repeat | 203: 20−6=14 → yes |
| 8 | Last three digits are divisible by 8 | 5,624: 624÷8=78 |
| 9 | Sum of digits is divisible by 9 | 7,452: sum=18 |
| 10 | Last digit is 0 | 12,340 |
| 11 | Alternating digit sum is divisible by 11 | 9185: 9−1+8−5=11 |
| 12 | Divisible by both 3 and 4 | 1,404 |
| 13 | Add 4× last digit to remaining number; repeat | 286: 28+24=52 |
| 14 | Divisible by both 2 and 7 | 686 |
| 15 | Divisible by both 3 and 5 | 2,145 |
| 16 | Last four digits divisible by 16 | 65,536 |
| 18 | Divisible by both 2 and 9 | 1,458 |
| 20 | Last two digits are 00, 20, 40, 60 or 80 | 3,480 |
How to use this table
Practical tests for checking divisibility without performing full division. Use it as a reference, for practice, or to check your own work. On large tables, scroll horizontally on a phone. Tap cells to visually track a row or value.