What Regrouping Actually Means

Regrouping — what used to be called "borrowing" — is what you do when you can't subtract because the top digit is smaller than the bottom digit. You trade one unit from the next place value, convert it to 10 of the current place value, and then subtract.

Example: 42 - 17. You can't do 2 - 7 because 2 is smaller than 7. So you trade one ten from the tens column (leaving 3 tens), convert it to 10 ones (making 12 ones), and now subtract: 12 - 7 = 5, and 3 - 1 = 2. Answer: 25.

It's place value in action. Every mistake in subtraction with regrouping traces back to a misunderstanding of place value.

When Kids Learn It

Subtraction with regrouping is typically introduced in 2nd grade and extended in 3rd grade. By the end of 3rd grade, kids should be fluent with regrouping across multiple columns and through zeros.

Download our worksheets to practice at each level:

Grade 2 subtraction worksheet PDF — 2-digit subtraction with regrouping
Grade 3 subtraction worksheet PDF — 3-digit subtraction with regrouping across zeros

Both include answer keys.

Teach It Concretely First

Don't start with the written algorithm. Start with base-10 blocks, or draw them on paper.

Set up 42 as 4 tens and 2 ones. Try to take away 17 (1 ten and 7 ones). Your child will immediately notice they can't take 7 ones because they only have 2.

That's the teachable moment: "We need to trade one ten for ten ones." Physically move a ten, break it into 10 ones. Now there are 3 tens and 12 ones. Subtract 7 ones, leaving 5. Subtract 1 ten, leaving 2. Answer: 25.

Do this 5-10 times with blocks or drawings before ever introducing the written procedure. Kids who skip this step memorize a mystery algorithm and make the same mistakes forever.

The Written Procedure

Once the concrete model is solid, show the written version:

Start with the ones column
Ask: "Can I subtract?" (Is the top number big enough?)
If no, go to the next column and "trade" — cross out the tens digit, reduce it by 1, and add 10 to the current column
Subtract the current column
Move to the next column

Say each step out loud the first few times. The verbal rehearsal cements the procedure.

Subtracting Across Zeros

The hardest version of regrouping is subtracting across zeros. Example: 300 - 156.

You can't borrow from 0 in the tens place, because 0 doesn't have anything to give. So you go one more column over to the hundreds, borrow 1 hundred (leaving 2 hundreds), which becomes 10 tens. Now the tens column has 10. Borrow one of those tens, and the tens column has 9. The ones column now has 10.

Subtract: 10 - 6 = 4. 9 - 5 = 4. 2 - 1 = 1. Answer: 144.

This is genuinely hard. Most 3rd graders need 10-15 problems before they can do this smoothly. The Grade 3 subtraction worksheet PDF includes zeros problems with plenty of practice.

Common Mistakes

Here's what to watch for:

Subtracting smaller from bigger in a column — if the top is 2 and the bottom is 7, they might subtract 7 - 2 = 5 instead of regrouping
Forgetting to reduce after borrowing — they add 10 to the ones column but don't cross out the tens
Borrowing from the wrong column — jumping past the next column to grab from further away
Not regrouping across zeros correctly — skipping the middle step

When you see one of these repeatedly, don't just correct the answer. Back up to base-10 blocks for a few problems so your child rebuilds the mental model.

Practice Tips

Start with problems that need regrouping in only one place. Then progress to multi-column regrouping.
Mix in problems that don't need regrouping — kids need to learn when it's needed and when it isn't.
Use graph paper or lined paper turned sideways. Place value confusion is the root cause of most mistakes; keeping columns lined up prevents half of them.
Work in short sessions. 10 problems at a time, done well, beats 30 done sloppily.

Free Printable Worksheets

Both worksheets are free, printable, and come with answer keys for quick checking.

Two weeks of 10 minutes a day, and regrouping moves from confusing to automatic.

Subtraction With Regrouping Worksheets (Printable)