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Subtracting With Borrowing (Regrouping)

After you learn how to subtract, you'll run into harder problems in which you'll need to borrow before you can complete subtraction. You'll need to borrow when the top number of your subtraction problem is not large enough to complete the subtraction of the bottom number. For example, if the ones' column read "3 - 9", you would need to borrow, because you cannot subtract 9 from 3. In this section, we'll take you through how to borrow in order to complete these types of problems.

Subtracting Two Digit Minus One Digit Numbers

Sometimes you may run into a problem that doesn’t seem possible, where the ones’ column does not subtract properly. When this happens, it means you have to borrow from the next digit in order to be able to subtract. For example, look at the following problem:

When you try to subtract the ones’ column, you see that you have 2 – 8, which is impossible! In order to do this, we have to “borrow” from the 3 (the number in the tens’ column). Borrowing only has a few steps, but they have to be done in the right order for the problem to work out. We have the steps listed for you below, so once you read and understand the first step, click "Step-by-Step" to move on.

Subtraction Steps

Step 1

Cross out the digit in the tens’ column. In our example, it is a 3. We’re going to cross it out in red, but you can cross it out in pencil or whatever you’re working with, like this:

Step 2

Above the number you just crossed out, write the number that is one less than the one you crossed out. For example, if you cross out a 3, write 2; if you cross out a 2, write 1, and so on. We are going to write our new number in red as well.

Step 3

In front of the ones’ digit, write a 1. You are actually making it a 2-digit number when you do this, so 2 becomes 12, 3 becomes 13, and so on. For our example, we started with 2, so we put a 1 (in red) in front of the two to make it 12. Here’s the diagram explaining this:

Step 4

Start your subtraction over again, starting with the ones’ column. Your new subtraction problem is 12 – 8. What is 12 – 8? We know that 12 – 8 = 4, so we write 4 in the ones’ column in the answer.

Step 5

Now you continue with the rest of the subtraction, which is in the tens’ column. Since you only have one digit in the tens’ column, you can bring it straight down into the tens’ column of the answer. This is shown with a red arrow in the diagram below.

Therefore, our final answer is 24, after the borrowing and subtraction.

Another Step-by-Step Subtraction Problem

Let’s try this again so that you can practice these steps of borrowing. Here’s the problem we’ll start with:

Steps 1-2

We’re going to combine some of the steps. Here are the first two steps:

Step 3

Now, here’s the third step:

Steps 4-5

Finally, here are the fourth and fifth steps, along with the final answer:

Therefore, if you followed all of the steps correctly, you got 36 as your answer! If you did not get 36 as your answer, re-read through each step to ensure you borrowed and subtracted correctly.

Subtracting Two Digit Minus Two Digit Numbers

Now, let’s try something a little bit harder. We’ll still be subtracting two digit minus two digit numbers, but now we’re going to show you how borrowing works. It’s very similar to two digit minus one digit numbers with borrowing, which we did earlier, but there’s one step that’s different.

Subtracting Two Digit Numbers

First, we’re going to start out with a two digit subtraction problem that looks like this:

Notice that when we start to subtract the ones’ column, we see that our problem would be 3 – 9, which we know we cannot do because 9 is bigger than 3. Thus, we have to go borrow from the digit in the tens’ column, which is the 8 in this example. Here are the steps to borrowing:

Step 1: Cross out the digit in the tens’ column. In our example, it is an 8. We’re going to cross it out in red, but you can cross it out in pencil or whatever you’re working with, like this:

Step 2: Above the number you just crossed out, write the number that is one less than the one you crossed out. For example, if you cross out a 3, write 2; if you cross out a 2, write 1, and so on. We are going to write our new number in red as well.

Step 3: In front of the ones’ digit, write a 1. You are actually making it a 2-digit number when you do this, so 2 becomes 12, 3 becomes 13, and so on. For our example, we started with 3, so we put a 1 (in red) in front of the three to make it 13. Here’s the diagram explaining this:

Step 4: Start your subtraction over again, starting with the ones’ column. Your new subtraction problem is 13 – 9. What is 13 – 9? We know that 13 – 9 = 4, so we write 4 in the ones’ column in the answer.

Step 5: Now you continue with the rest of the subtraction, which is in the tens’ column. This is where the step differs from before. Previously, we just brought the top number straight down, because there was only one digit in the tens’ column. Now, there are two digits in the tens’ column, so we can subtract them. In the tens’ column, we have 7 – 4, which equals 3. Thus, we write a 3 in the tens’ column of the answer, like this:

Thus, your final answer is 34.

One more example...

Let’s try this one more time to make sure you understand how to borrow with two-digit numbers. Here’s another problem for you to practice with:

Now, using the above listed steps, try solving the problem. We’ll solve it here as well, so that you can compare your answer to ours:

Thus, the final answer is 16. If you did not get 16, re-read the steps very closely to ensure that you didn’t skip or miss a step. If you did get 16, congrats! You’re absolutely right!

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