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🔢 Multi-Digit Subtraction with Borrowing

2-3 Math ⏱ 35 min Prep: none No Prep Parent Led
Materials: Paper, pencil, base-10 blocks or coins (optional), calculator for checking

Subtraction with borrowing is one of those skills that can feel like magic until your child understands what is actually happening. The good news: once they get it, they will never forget it.

What You Need

You already have everything. Paper, pencil, and maybe some base-10 blocks if you have them. If not, coins work too - pennies, dimes, and a few quarters.

What To Do

Start with a problem they can visualize. 1. Write: 42 - 18 = 2. Set it up vertically with 42 on top, 18 below. 3. Ask: "Can I take 8 ones from 2 ones?" Let them think. They will probably say no. 4. Say: "Exactly. So we need to borrow from the tens." 5. Point to the 4 in the tens place. Say: "This 4 is actually 40. One ten is 10 ones." 6. Cross out the 4, write a small 3 above it. Cross out the 2, write a 12 next to it. 7. Say: "Now I have 12 ones. Can I take 8 from 12? Yes! That leaves 4." 8. Cross out the 8, write 4 below. Then move to the tens: "3 - 1 = 2." 9. Write: 24

Do a few together. - 53 - 27 - 61 - 34 - 82 - 46

Let them call out each step. Write the problem, ask "Can I take it?" then guide them through.

Move to independent practice. Once they are comfortable, let them try two or three on their own. Check work as they go. If they make a mistake, go back to the borrowing step.

Why This Works

Children struggle with this because it is abstract. They can see 42, they can see 18, but they cannot see what "borrowing" actually does. That is why the crossed-out numbers and the small 10 matter - they make the invisible visible.

The other reason it is hard: it has multiple steps. Each step is simple. But do 4-5 of them in a row and even adults get tired. That is normal.

Pro Tips

  • Let them use base-10 blocks the first few times. It helps them see that 42 really is 4 tens and 2 ones.
  • If they struggle, go back to just ones and tens. 32 - 15. No hundreds. Once they get that, add hundreds.
  • Have them check their work with a calculator. It builds confidence when the answer matches.
  • Praise the process, not the answer. "You got the borrowing right" is more important than "you got 27."

Common Mistakes

  • Subtracting the smaller number from the bigger number in each column without borrowing first. (6 - 9 becomes 3, not -3.)
  • Forgetting to cross out the tens and write the new number. (Cross out the 5 in 53, write 4. This is easy to skip.)
  • Subtracting across the wrong columns. (4 - 8 in the ones, 2 - 1 in the tens.)
  • Borrowing when they should not have to. (43 - 21 - no borrowing needed. But some kids do it anyway.)
💬 Parent Script

Set up the problem. Ask: "Can I take the bottom number from the top in the ones column?" If yes, do it. If no, say: "We need to borrow. Watch what happens." Then do it slowly: cross out the tens digit, write the smaller number above it, add 10 to the ones digit. Let them say what to do next. Once they can do it independently, give them two or three problems to do on their own.

⚠️ Common Mistakes to Watch For
  • Going straight to the borrowing without checking if they actually need to. Not every subtraction requires borrowing.
  • Making the mistake where they subtract the smaller from the bigger number. This is the most common error.
  • Forgetting to update the tens after borrowing. They cross out the 5, but never write the 4.
  • Doing the borrowing in the wrong direction. You borrow from the column to the left, not the right.
  • Rushing. This takes time. Let them write the small numbers clearly so they do not lose track.
🔽 If Your Child Struggles

Go back to base-10 blocks or coins. Physical objects make it concrete. Let them trade 1 ten block for 10 ones. Count them together. Then set up the problem on paper and do the same thing with the pencil. Or start with numbers that do not cross zero. 52 - 34 is easier than 50 - 34. Once they are solid, add the harder ones.

🔼 Challenge Version

Add hundreds: 342 - 156. Or introduce three-digit numbers where borrowing is needed in both columns. 403 - 127 requires borrowing twice. For very advanced kids, let them create their own problems and trade with a sibling or parent.

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