How to use it
- Choose an amount that makes the second number end in 0 or 00.
- Add that amount to both numbers.
- Subtract the friendlier pair.
See it in action
503 − 198 → 505 − 200 = 305.
How to verify it
Reverse-check: 305 + 198 = 503.
Subtract by Compensation
Add the same amount to both numbers so the subtrahend becomes friendly.