Divisibility Rule for 9
✅ Shortcut: Add all the digits of the number. If the total is divisible by 9, then the whole number is divisible by 9.
Examples:
| Number | Sum of Digits | Divisible by 9? | Reason |
|---|---|---|---|
| 729 | 7 + 2 + 9 = 18 | ✅ Yes | 18 ÷ 9 = 2 |
| 123 | 1 + 2 + 3 = 6 | ❌ No | 6 ÷ 9 = 0.666 |
| 9999 | 9 + 9 + 9 + 9 = 36 | ✅ Yes | 36 ÷ 9 = 4 |
| 2527 | 2 + 5 + 2 + 7 = 16 | ❌ No | 16 ÷ 9 = 1.77 |
| 8019 | 8 + 0 + 1 + 9 = 18 | ✅ Yes | 18 ÷ 9 = 2 |