How to quickly subtract numbers

Suppose you are subtracting 28 from 65. Doing vertical subtraction is fine. However, if you are pressed for time and you need to get an answer quick, this is not the time to set up vertical subtraction and then do borrowing and regrouping.

Here is the trick: Subtract 30 from 65 to get 35 and then add 2 since you subtracted 2 more than what you were supposed to. The answer is 37.

Again, we do this because it is kind of easy to subtract tens from any number.

Example #10

461 – 297

461 – 300 = 161

161 + 3 = 164

You would not have found the answer in a snap of a finger had you done vertical subtraction with borrowing and regrouping.