When we were at school, we really only learned the one traditional way to subtract numbers. This is where you subtract from left to right. We called it carrying or borrowing, and it’s now called re-grouping. You may remember this?
Traditional Method to Subtract
Let’s say we are subtracting 156 from 360.
We start from the right, and immediately have to borrow.
Then you subtract the tens column.
And finally, the hundreds column – the left column.
And there’s your answer.
However, there are easier ways to help our kids learn to subtract. Here are some of those methods. We call them mental math, Singapore method and counting up.
Mental Math
In mental math you subtract from left to right. You start with the hundreds. So, 360 – 100.
Then the tens, so 260 – 50.
And finally the ones column: 210 – 6.
Singapore Method
In the Singapore method, you don’t have to carry over the number. In our example, 6 is greater than 0. So to avoid carrying, we’ll subtract 6 from both numbers.
Subtract 6 from the top line:
Subtract 6 from the bottom line:
And then subtract the sums of those numbers, which is now a straight subtraction with no carrying:
Counting Up
This is a good for example for when you need to give change.
In this method, you start from the lower number and count up to the top number.
So we start with $1.56 and count up to $3.60.
First, let’s add up to tens. Adding 4 to 1.56 brings it up to 1.60.
Then, add up to 100s. Adding 50 to 1.60 brings you up to 2.00.
Then, keep counting up. Adding 1 to 2, brings us up to 3.00.
And finally, let’s add the .6 to 3 to bring it to 3.60.
To work out the difference between 1.56 and 3.60, you now add the numbers in orange.
0.60 + 0.4 + 1 + 0.04 = 2.04
If you are looking for practice sheets for subtracting larger numbers in columns, check out our grade 4 subtraction worksheets:
