How to Help With Grade 2 Subtraction With Borrowing

Grade 2 subtraction with borrowing is the point where many children stop being able to solve every problem by counting back. The goal is not just to remember a rule. Students need to understand that one ten can be traded for ten ones, so a column has enough ones to subtract.

What your child is learning

In Ontario Grade 2 math, subtraction grows from facts within 20 into two-digit and early three-digit work. A problem like 43 - 18 asks the student to look at the ones column first: 3 ones cannot subtract 8 ones, so 1 ten is regrouped as 10 ones. The number 43 becomes 3 tens and 13 ones, and the subtraction can continue.

This belongs in Strand B, Number, where students use place value and the relationship between addition and subtraction to solve problems. A useful parent question is: "What did you trade, and why?" If your child can answer that, they are learning the concept, not just copying the algorithm.

Three common sticking points

1. Borrowing when it is not needed

Example: in 57 - 23, some students cross out the 5 even though 7 - 3 is already possible. Ask them to check the ones column first: "Do you have enough ones?" If yes, subtract without regrouping.

2. Forgetting to reduce the tens digit

Example: in 43 - 18, a child may write 13 - 8 = 5 but leave the tens digit as 4. Use base-ten language: 43 became 3 tens and 13 ones, not 4 tens and 13 ones. The answer is 25, not 35.

3. Not checking with addition

Example: if 43 - 18 = 25, then 25 + 18 should return 43. This check is simple enough for Grade 2 and catches most regrouping mistakes without needing a parent to redo the whole worksheet silently.

How to practise

Start with short sets. Five careful borrowing problems are more useful than a full page done quickly with repeated errors. Mix in a few no-borrow problems so your child has to decide whether regrouping is needed instead of assuming every problem uses the same move.

• Grade 2 subtraction worksheets
• Grade 2 subtraction with borrowing worksheets
• Grade 2 three-digit subtraction practice
• Grade 2 subtraction word problems
• Ontario Grade 2 math expectations

How to check the work

For one or two problems, ask your child to add the answer back to the number subtracted. For a full page, photo checking is faster and gives feedback on the steps, which matters when the final answer is wrong because of one small regrouping slip.

• Use the math checker tools
• Check Grade 2 math homework from a photo