How to teach carrying in addition (regrouping), step by step
Grades 1–45 min read
If your child’s homework says “regroup” and you learned it as “carrying,” you are talking about the same thing. Ten ones become one ten. Ten tens become one hundred. That is the whole idea.
The trouble is that kids can follow the steps without knowing why the little 1 goes where it goes. This guide walks through how I explain it, in the order I explain it, so the method makes sense and sticks.
What carrying actually means
Every column in a number can only hold one digit, from 0 to 9. When a column adds up to 10 or more, it has too much. So we trade: ten in this column become one in the column to the left.
That is why the carried digit is almost always a 1 when you add two numbers. Two digits can add up to at most 18, so there is never more than one group of ten to pass along. With three or more numbers in a column, you can carry a 2 or more.
Before you show the written method, check that your child can say what the digits in a number are worth. In 47, the 4 is worth forty and the 7 is worth seven. If that is shaky, start with our guide to place value and column alignment first. Carrying is place value in action.
Start with something they can hold
Ten pennies and a dime work well. So do bundles of ten straws with a rubber band, or base-ten blocks if the school sent some home.
Lay out 47 as four bundles and seven loose straws. Then 38 as three bundles and eight loose. Push the loose ones together and count them: 15. Ask, “Can we make a bundle?” Your child wraps ten of them and now has one new bundle and five loose straws.
Count the bundles: four, three, and the new one makes eight. Eight tens and five ones. That is 85, and the new bundle is the carried 1.
The written method with a two-digit problem
Here is 47 + 38 the way it is taught in most classrooms.
- 1Line the numbers up on the right so ones sit under ones and tens sit under tens.
- 2Add the ones column first: 7 + 8 = 15.
- 3Fifteen is one ten and five ones. Write the 5 in the ones place of the answer. Write a small 1 above the tens column.
- 4Add the tens column, including the carried 1: 1 + 4 + 3 = 8.
- 5Write 8 in the tens place. The answer is 85.
Every step, the way the pad explains it
- Add the ones: 7 + 8 = 15. Write 5, carry 1.
- Add the tens (with the carry): 1 + 4 + 3 = 8. Write 8.
Say the place names out loud while you work. “Seven ones plus eight ones is fifteen ones. That is one ten and five ones.” It sounds slow, but it keeps the meaning attached to the digits.
Carrying more than once
Once two-digit problems feel easy, move to three digits. The steps do not change. You just keep going left.
Take 478 + 256. Ones: 8 + 6 = 14, so write 4 and carry 1. Tens: 1 + 7 + 5 = 13, so write 3 and carry 1 again. Hundreds: 1 + 4 + 2 = 7. The answer is 734.
Every step, the way the pad explains it
- Add the ones: 8 + 6 = 14. Write 4, carry 1.
- Add the tens (with the carry): 1 + 7 + 5 = 13. Write 3, carry 1.
- Add the hundreds (with the carry): 1 + 4 + 2 = 7. Write 7.
When the last column also makes ten or more, the carried 1 has nowhere to sit, so it drops straight down into a new place in the answer. In 695 + 487, the hundreds come to 1 + 6 + 4 = 11, and the answer is 1182.
Every step, the way the pad explains it
- Add the ones: 5 + 7 = 12. Write 2, carry 1.
- Add the tens (with the carry): 1 + 9 + 8 = 18. Write 8, carry 1.
- Add the hundreds (with the carry): 1 + 6 + 4 = 11. Write 1, carry 1.
- Nothing left to add in the thousands place — the carried 1 drops straight down into the answer.
The mistakes I see most
Writing the whole number in the answer
A child adds 7 + 8, gets 15, and writes 15 under the ones column. The answer to 47 + 38 comes out as 715. Go back to the straws: can one column hold fifteen? No. Only one digit fits, so the ten has to move.
Forgetting to add the carry
They write the small 1, then add 4 + 3 = 7 and ignore it. The answer comes out ten too small. Have them touch the carried digit with their pencil first, every time, before they add the column.
Carrying from the wrong side
Some kids start on the left because that is how we read. Explain that we start with the ones because a carry can change the column next door, and carries only ever move left.
Numbers that are not lined up
With 352 + 46, a child may line up the 4 under the 3. Turn lined paper sideways so the lines make columns, or use graph paper with one digit per square.
Short practice that works
Five problems done carefully beat a page of thirty done in a rush. Here is a simple routine for a school night:
- One problem with no carrying, so they start with a win.
- Two problems that carry once.
- One problem that carries twice.
- One problem they make up for you to solve. Make a mistake on purpose and let them find it.
Ask them to estimate first. For 478 + 256, about 480 plus about 260 is about 740, so an answer of 634 or 7314 should feel wrong straight away. Estimating is the habit that catches most carrying slips.
When carrying is solid, the same thinking runs backwards in subtraction. Our guide to borrowing across zeros picks up from here, and the addition with regrouping practice page has a quick summary you can keep open next to the homework.
How MathPad handles carrying
On the MathPad pad, each digit gets its own box and the carry boxes sit right above the columns, the way they would on paper. MathPad checks each digit as your child types it. A wrong digit gets a gentle nudge first, and a second miss gets a hint about that step, not the answer.
When the last column carries, your child writes the 1 above the empty column and the pad drops it into the answer, which is a nice way to show where that extra digit comes from.
Questions parents ask
- Is carrying the same as regrouping?
- Yes. Regrouping is the word most schools use now because it describes what happens: ten ones are regrouped as one ten. Carrying is the older name for the same step.
- What grade do kids learn carrying in addition?
- Most children meet it in second grade with two-digit numbers and use it with three-digit numbers by third grade. By fourth grade they are expected to add multi-digit numbers with the standard method fluently.
- Can you ever carry a 2?
- Not when you add two numbers, because one column can add up to at most 18. When you add three or more numbers, a column can reach 20 or more, and then you carry a 2 or more.