Divisibility Rule for 7
✅ Shortcut: Take the last digit, double it, subtract from the rest. If the result is divisible by 7, so is the original number.
Examples:
| Number | Step | Result | Divisible by 7? |
|---|---|---|---|
| 203 | 20 − (2×3) | 14 | ✅ Yes |
| 301 | 30 − (2×1) | 28 | ✅ Yes |
| 259 | 25 − (2×9) | 7 | ✅ Yes |
| 321 | 32 − (2×1) | 30 | ❌ No |
| 161 | 16 − (2×1) | 14 | ✅ Yes |