Knowing mental math tricks is a critical skill in math. Knowing how to do this you will be able to work out sums in your head more rapidly . Here are examples of some mental math strategies for subtraction.
Compatible Number Estimation
We use compatible numbers to estimate the answer. To use this estimation strategy, change the actual numbers to compatible numbers. For example:
Front-End Strategy
When there is no need to carry, you can use the front-end strategy by subtracting from left to right - subtract the hundreds, then the tens and then the ones. For example:
Front-end Estimation
For questions where there is no need for carrying in the highest two place values, simply subtract those place values for a quick estimation. For example:
Compatible Numbers
This works well for powers of 10. What number will make the power of 10? For example:
Equal Additions Strategy
This is a strategy that avoids regrouping. You add the same number to the subtrahend and the minuend for a “friendly” number for subtracting. For example:
Compensation Strategy
Here you identify the “friendly” number first and then add the difference. For example:
Counting On
Think of the numbers on a number line. For example:
Counting On Estimation
The same number line strategy can be used for estimation. For example:
K5 Learning offers a number of free printable mental subtraction worksheets in its math worksheet center across grades 1 to 6. Here are the mental subtraction worksheets for grade 1, grade 2, grade 3 and grade 4.
