3-Digit Addition with Carrying (Regrouping)

Learn 3-digit addition with carrying the easy way — watch each step animate: add the column, carry the ten, and write the digit. Then read the full method with worked examples.

What is 3-digit addition with carrying?

Carrying (also called regrouping) happens when the digits in a column add up to 10 or more. Since each place can only hold a single digit (0–9), you write the ones digit of the sum in that column and carry the extra ten into the next column on the left. Use the animation above to watch each carry happen step by step for 20 different problems, then follow the written method below.

The method — step by step

Line up the numbers by place value: hundreds under hundreds, tens under tens, ones under ones.
Start from the ones (right-most) column. Add the two digits.
If the sum is 9 or less, just write it below the line.
If the sum is 10 or more, write the ones digit and carry 1 to the top of the next column on the left.
Move left to the tens, then the hundreds — each time adding the two digits plus any carry.
If the hundreds column carries, that final 1 becomes the thousands digit of the answer.

Worked example: 548 + 459

Column	What happens	Write / Carry
Ones	8 + 9 = 17	Write 7, carry 1
Tens	4 + 5 + 1 (carried) = 10	Write 0, carry 1
Hundreds	5 + 4 + 1 (carried) = 10	Write 0, carry 1
Thousands	final carry	Write 1

So 548 + 459 = 1007.

A simpler example: 386 + 247

Ones: 6 + 7 = 13 → write 3, carry 1. Tens: 8 + 4 + 1 = 13 → write 3, carry 1. Hundreds: 3 + 2 + 1 = 6 → write 6. Answer: 633.

Common mistakes to avoid

Forgetting to add the carry into the next column — the carried 1 must be included in that column's sum.
Writing the whole two-digit sum in one column (e.g. writing 17 in the ones place) instead of writing 7 and carrying 1.
Not lining up place values, which makes you add the wrong digits.
Dropping the final carry — if the hundreds add to 10 or more, remember the answer has a thousands digit.

Practice problems

Try these in the animation above (tap “Choose a problem”): 765 + 158, 657 + 289, 356 + 485, 267 + 398, 729 + 193, 318 + 594. Add each on paper first, then play the steps to check your carries.

Quick tip

Carrying is just trading: 10 ones = 1 ten, and 10 tens = 1 hundred. When a column reaches 10, you trade ten of the smaller units for one of the next larger unit — the total value never changes, which is why the answer stays correct.