Learn Carry
Introduction
When digits in a column add up to 10 or more, we "carry" the extra ten to the next column. This process — called regrouping — is the key technique in multi-digit addition.
What is Carrying (Regrouping)?
Carrying happens when the sum in a column is 10 or greater. In our base-10 number system, 10 ones = 1 ten, 10 tens = 1 hundred, and so on. When a column overflows, we regroup by moving one unit to the next higher place value.
Step-by-step process: 1. Add the digits in the ones column. 2. If the sum is ≥ 10: write the ones digit, carry the tens digit to the next column. 3. Add the tens column digits, including the carry. 4. Repeat for each column.
Think of carrying as trading: 10 pennies → 1 dime. You exchange 10 small units for 1 larger unit.
The Carrying Process — Step by Step
Example: 58 + 37 = ?
Step 1 (Ones): 8 + 7 = 15. Write 5 in the ones place, carry 1 to the tens column. Step 2 (Tens): 5 + 3 + 1 (carry) = 9. Write 9 in the tens place. Result: 95
Verification: 95 − 37 = 58 ✔
The carry digit (1) represents one group of ten. Adding it to the tens column accounts for the extra ten produced in the ones column.
Quick practice
Using a sample question until this lesson includes practice data. XP sync rolls out with account progress (Phase 4).
Quick warm-up: what is 4 + 3?
For the full tabbed flow with scoring summary, open the Practice tab above.