Subtraction
Subtracting in your head
Remember, you can always jot down numbers on paper while you are subtracting in your head.
For simple numbers, you can try to subtract them in your head. You can make it easier by:
Remember, you can always jot down numbers on paper while you are subtracting in your head.
For simple numbers, you can try to subtract them in your head. You can make it easier by:
- Breaking up numbers
63 - 37 is the same as 63 - 30 - 7
63 - 30 = 33
33 - 7 = 26 - Rounding numbers
63 - 37 is the same as 63 - 40, then adding 3
63 - 40 = 23
23 + 3 = 26 - Counting on
To work out 63 - 37, count on from 37 to 63
Count on from 37 to 40 to get 3
Count on from 40 to 60 to get 20
Count on from 60 to 63 to get 3
3 + 20 + 3 = 26
Writing it down
If the numbers are too high or too difficult to subtract in your head, write them down in columns. Always start subtracting with the units first.
If the numbers are too high or too difficult to subtract in your head, write them down in columns. Always start subtracting with the units first.
Useful tips
- Estimate first and check afterwards
It's a good idea to estimate a rough answer first. And always check your actual answer. - Subtraction is the opposite to addition
So subtraction can always be checked by adding. To check that 82 - 37 = 45, add the 45 and the 37 and you should get 82.
82 - 37 = 45
37 + 45 = 82 - Spot the key words
Look out for these words in problems: take away, difference, less than, minus, decrease, fewer than, reduce. They all indicate a subtraction calculation.