Subtract two-digit numbers - no regrouping
Theory
Subtracting two-digit numbers with no regrouping is a Year 3 maths skill: split each number into tens and ones, then take the ones from the ones and the tens from the tens. This page shows the column method, the split strategy and counting back on a number line, and explains what "no regrouping" means. Curriculum: VC2M3N04 / AC9M3N03.
A two-digit number is built from tens and ones. To subtract is to take one number away from another. The answer is called the difference.
With no regrouping, you never have to borrow from the next column. This happens when the top ones digit is bigger than or the same as the bottom ones digit, so each column can be subtracted on its own. In \(59 - 34\) the ones give \(9 - 4 = 5\) and the tens give \(5 - 3 = 2\), so the difference is \(25\).
Two easy ways to do it: the column method lines the numbers up and subtracts each column, and the split strategy subtracts the tens and the ones separately, then adds the parts back together.
Subtraction has no formula, but these facts help with every question in this topic.
How to subtract two-digit numbers with no regrouping
- Line them up. Write the numbers with ones under ones and tens under tens.
- Subtract the ones. Take the bottom ones digit from the top ones digit.
- Subtract the tens. Take the bottom tens digit from the top tens digit, then read the two answers together.
| \(\text{Ones}\) | \(:\) | \(6 - 2 = 4\) |
| \(\text{Tens}\) | \(:\) | \(7 - 4 = 3\) |
| \(76 - 42\) | \(=\) | \(34\) |
The difference is \(34\).
| \(80 - 40\) | \(=\) | \(40\) |
| \(9 - 7\) | \(=\) | \(2\) |
| \(40 + 2\) | \(=\) | \(42\) |
So \(89 - 47 = 42\).
| \(78 - 20\) | \(=\) | \(58\) |
| \(58 - 6\) | \(=\) | \(52\) |
Jump back \(20\) then \(6\), so \(78 - 26 = 52\).
| \(90 - 50\) | \(=\) | \(40\) |
| \(5 - 2\) | \(=\) | \(3\) |
| \(40 + 3\) | \(=\) | \(43\) |
Zoe has \(\$43\) left.
Common pitfalls
Frequently asked questions
How do you subtract two-digit numbers?
Line up the numbers so ones sit under ones and tens under tens. Subtract the ones first, then subtract the tens. For \(59 - 34\) the ones give \(9 - 4 = 5\) and the tens give \(5 - 3 = 2\), so the answer is \(25\).
What does no regrouping mean in subtraction?
No regrouping means you never have to borrow from the next column. It happens when the top ones digit is bigger than or equal to the bottom ones digit, so each column can be subtracted on its own.
What is the split strategy for subtraction?
The split strategy subtracts the tens and the ones separately, then adds the parts back together. For \(89 - 47\) you work out \(80 - 40 = 40\) and \(9 - 7 = 2\), then \(40 + 2 = 42\).
How do you know if you need to regroup or borrow?
Look at the ones column. If the top ones digit is smaller than the bottom ones digit, you need to regroup. If the top ones digit is bigger or the same, no regrouping is needed.
What does difference mean in maths?
The difference is the answer to a subtraction. It tells you how much is left, or how much bigger one number is than another. The difference of \(76\) and \(42\) is \(34\).
How do you check a subtraction answer?
Add the answer back to the number you took away. If \(78 - 26 = 52\), then \(52 + 26\) should equal \(78\). If it does, the subtraction is correct.