The fast method
⚡
1800 - 18 = 1782.
How it works
Multiply by 100 and subtract the original number. 99n = (100 - 1)n.
Why it works
99n = (100 - 1)n.
Use it when
Works for any real number.
Watch out for
Keep place values aligned during subtraction.
Verified examples
Example 1
18 × 99
1800 - 18 = 1782.
1782Example 2
46 × 99
4600 - 46 = 4554.
4554Example 3
125 × 99
12500 - 125 = 12375.
12375