Addition and Subtraction With Regrouping: A Simple Guide
Regrouping just means exchanging between place-value columns. In addition we call it carrying; in subtraction we call it borrowing. Both follow a simple, repeatable pattern that this guide walks through.
Addition with carrying
Add each column from the right. If a column totals 10 or more, write the ones digit and carry the ten to the next column.
Ones: 7 + 8 = 15 → write 5, carry 1.
Tens: 6 + 5 + 1 (carried) = 12 → write 2, carry 1.
Hundreds: 3 + 1 + 1 (carried) = 5 → write 5.
Answer: 525
Subtraction with borrowing
Work right to left. If the top digit is smaller than the bottom digit, borrow 1 from the next column to the left (it becomes 10 more in the current column).
Ones: 3 − 7 won't work, so borrow. The 0 in the tens is empty, so borrow from the hundreds first.
After regrouping: ones become 13 − 7 = 6.
Tens: 9 − 4 = 5.
Hundreds: 4 − 2 = 2.
Answer: 256
Common mistakes to avoid
- Forgetting to add the carried digit into the next column.
- Borrowing across a zero — remember it may take two steps.
- Lining digits up incorrectly. Keep ones under ones, tens under tens.
How to practice
The free Regrouping Calculator shows every carry in blue and every borrow in red, column by column — perfect for checking homework or modeling the method. You can also make a printable practice set with the worksheet generator.
Frequently asked questions
What does regrouping mean?
Exchanging between place-value columns — carrying in addition, borrowing in subtraction.
When do I carry?
Whenever a column in an addition totals 10 or more: write the ones digit and carry the ten left.
Where can I see the steps?
Use the free Regrouping Calculator to see each carry and borrow.