**What is borrowing (regrouping) in subtraction?**

Borrowing, or regrouping, is a process that happens when the digits in a single column can’t be subtracted. You move to the next highest column and borrow one digit. That makes the number in the higher column decrease by one, and it makes the number in the lower column increase by 10. Here’s why:

**How to subtract two-digit numbers with borrowing (regrouping):**

*Note: The steps below are for subtracting when borrowing is required. If the numbers you’re subtracting don’t require borrowing, you can head to our double-digit subtraction without regrouping page to see step-by-step instructions to follow. *

**Step 1:** Start with the numbers in the ones column. If the number you’re subtracting is larger than the number above, you’ll need to borrow from the tens column.

**Step 2:** “Move to the next column. Take away 1. Add 10.”

**Step 3:** Subtract the numbers in the ones column, and write your answer under the solution bar (in the ones column).

**Step 4:** Subtract the numbers in the tens column, and write your answer under the solution bar (in the tens column).

**Example: Find the solution to 45 – 29.**

**Are there any tips for teaching two-digit subtraction with borrowing to children?**

- Stay patient: Some children have trouble picking up on the process. You may be tempted to think they’ll never get it, but they will.
- Practice: If the process seems confusing, the best thing to do is practice. With enough repetition, the process will start to sink in.
- Keep it simple: Don’t introduce too many tricks or hacks. Regrouping is a fundamental skill that helps students with number sense. If they can understand the process of regrouping now, then any tricks they learn later will make more sense.

**What are some common mistakes to avoid when subtracting two-digit numbers with borrowing?**

The most common mistakes come from not following the process in order. If you can’t subtract two numbers because the bottom one is larger than the top, then step one is “move to the next column.” Then, take away one. Then add 10. Students will be tempted to add 10 before taking away one. Though you can technically do that on paper, it increases the chances that the student will forget to lower the number in the higher place value. When this happens, students will get the wrong answer.

Another mistake happens when students don’t process the problem accurately. If the digit on top is 5 and the digit being subtracted is 7, some students will automatically write an answer of 2. If you see this happening consistently, have them read the problem out loud. Things can easily get jumbled in our heads, but when we say the problem out loud it tends to help with understanding.