Subtract whole numbers (written strategies) - No regrouping
Theory
To subtract whole numbers, line them up by place value with the larger number on top and subtract each column, starting from the ones. When every top digit is big enough, no borrowing is needed — subtraction without regrouping.
The subtraction algorithm takes one number away from another by writing them in columns, larger number on top.
Subtract each column from the right — top digit minus bottom digit — and write each answer underneath.
When every top digit is big enough, no borrowing is needed. This is subtraction without regrouping.
Set the numbers out so every digit sits in its place-value column, larger number on top.
| Thousands | Hundreds | Tens | Ones |
|---|---|---|---|
| 7 | 8 | 5 | 6 |
| 3 | 4 | 2 | 1 |
| 4 | 4 | 3 | 5 |
How to subtract without regrouping
- Write the larger number on top, ones under ones.
- Subtract each column from the right: top digit minus bottom digit.
- Write each answer underneath to build the difference.
Each column: \(7-3\), \(8-4\), \(5-2\).
| \(587 - 243\) | \(=\) | \(344\) |
No column needs a borrow.
| \(7856 - 3421\) | \(=\) | \(4435\) |
| \(48\,765 - 12\,342\) | \(=\) | \(36\,423\) |
| \(6879 - 4523\) | \(=\) | \(2356\) |
There are \(2356\) m left.
Common pitfalls
Frequently asked questions
How do you subtract large numbers?
Write them in columns with the larger number on top, then subtract each column from the right: top digit minus bottom digit.
What does subtracting without regrouping mean?
Every top digit is big enough to take the bottom digit from, so you never need to borrow. \(7856 - 3421 = 4435\).
Which number goes on top?
The larger number, the one you are subtracting from, goes on top. You take the bottom number away from it.
Why do you start from the ones?
Working right to left keeps each digit in its place and prepares you for subtractions that do need borrowing.