# Using Base Ten Blocks to Subtract Two Digit Numbers (With regrouping)

Content Using Base Ten Blocks to Subtract Two Digit Numbers (With regrouping)
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## Subtraction with Base Ten Blocks with Regrouping

In order to subtraction with regrouping and base ten blocks, let’s first talk about: what does subtraction with regrouping mean, sometimes called subtraction with exchange.

What Does Subtraction with Regrouping Mean? To Subtract means to take away from a group. Sometimes when we are subtracting, there is not enough to take away. When this happens, we regroup, or exchange with another place value so that we can continue solving. We practise regrouping with base-ten blocks on a place value chart because these tools help us see what's happening when we regroup, or borrow.

## Subtraction with Base Ten Blocks and Regrouping – Rules

When practising subtraction with regrouping with base ten blocks, it is important to write down the problem with the larger number first. As you go through and subtract, keep track of what you are doing on the place value chart and in the answer. The next section will show an example of 2 digit subtraction with regrouping using base ten blocks. Pay close attention to the steps for solving 2 digit subtraction with regrouping with base ten blocks, so you can see these rules in action!

## Subtraction with Base Ten Blocks and Regrouping – Example

How do you subtract with regrouping? Let’s take a look at this example of subtraction with base ten blocks regrouping from the video.

There were seventy-five ducks in the water, and Mr. Squeaks took eighteen out. In order to see how many ducks are left, we will subtract seventy-five and eighteen using the place value chart and base ten blocks.

The first step is to represent how many ducks they started with. There were seventy-five in the water, so we'll use base ten blocks to represent seventy-five. Since there is a seven in the tens place, we put seven tens in the tens column.

There is a five in the ones place, so we put five ones in the ones column.

The second step is to subtract eighteen starting with the ones place so subtract eight from five. Can we take away eight from five? No! There are not enough blocks! Since there is not enough blocks to take away, we regroup, or exchange a ten from the tens place for ten ones.

Now there are fifteen blocks in the ones place that we can subtract eight from to get seven. Be sure to record the seven on the place value chart.

The third step is to subtract the tens place, so subtract one ten from six tens to get five tens. Be sure to record your answer on the place value chart.

Seventy-five minus eighteen equals fifty-seven!

## Subtraction with Base Ten Blocks and Regrouping – Summary

Remember when subtracting two-digit numbers using base ten blocks with regrouping follow these steps:

Step # What to do
1 Represent the number we started with on
the place value chart using base ten blocks.
2 Regroup from the tens place if you need to,
and then subtract the ones place and write
the difference below.
3 Subtract the tens place and write
the difference below.
4 The number remaining is the answer.

Want some more subtraction with more than one exchange practice? On this website there is a subtraction with regrouping using base ten blocks worksheets and interactive subtraction with regrouping base ten blocks exercises, along with other activities.

### TranscriptUsing Base Ten Blocks to Subtract Two Digit Numbers (With regrouping)

Mr. Squeaks is helping with the annual Rubber Duck Race but things have gotten out of hand. "Malfunction, malfunction!" Good thing Mr. Squeaks has this net so he can take out all the extra ducks! But how many ducks are left? In order to see how many ducks we have for the race, Mr. Squeaks needs our help with subtracting two-digit numbers using base ten blocks with regrouping. Mr. Squeaks placed seventy-five rubber ducks in the water, and took eighteen out. Let's subtract eighteen from seventy-five using base ten blocks on a place value chart to see how many are left. We can use a place value chart and base ten blocks to model subtraction. These tools help us see what's happening when we regroup, or exchange. The first step is to represent how many ducks they started with. There were seventy-five in the water, so we'll use base ten blocks to represent seventy-five. Since there is a seven in the tens place, we put seven tens in the tens column. There is a five in the ones place, so we put five ones in the ones column. The second step is to subtract eighteen starting with the ones place so subtract eight from five. But, we can't take away eight blocks because there are only five! Since there are not enough blocks to take away, we regroup, or exchange, a ten from the tens place for ten ones. Now there are fifteen blocks in the ones place that we can subtract eight from. If we take eight ones from the ones place, we have seven left. Write seven in the ones place here. The third step is to subtract the tens place, so subtract one ten from six tens. If we take one ten from the tens place, we have five left. Write five in the tens place here. Seventy-five minus eighteen is fifty-seven, but fifty-seven rubber ducks is still too many! Mr. Squeaks takes out thirty-nine more. Let's subtract thirty-nine from fifty-seven to see how many ducks are left. First, represent fifty-seven using base ten blocks. What number is in the tens place? There is a five in the tens place, so we put five tens in the tens column. What number is in the ones place? There is a seven in the ones place, so we put seven ones in the ones column. The second step is to subtract thirty-nine starting with the ones place so subtract nine from seven. Can we subtract nine blocks from seven blocks? No, we can't take away nine blocks because there are only seven. What can we do? We can regroup a ten from the tens place and exchange one ten for ten ones. Now, there are seventeen blocks in the ones place. If we take nine ones from the ones place, we have eight left. Write eight in the ones place here. The third step is to subtract the tens place, so subtract three tens from four tens. If we take three tens from the tens place, we have one left. Write one in the tens column here. Fifty-seven minus thirty-nine is eighteen, so there are eighteen rubber ducks left. Before we see if that's the right amount for the race, let's summarise. Remember, when subtracting two-digit numbers using base ten blocks with regrouping, the first step is to represent the number we started with on the place value chart using base ten blocks. Next, regroup from the tens place, making an exchange if you need to, and then subtract the ones place. Write the difference in the ones place here. Next, subtract the tens place and write the difference below. The number remaining is the answer. It looks like Mr. Squeaks wants to add one last rubber duck! "Oops!"

## Using Base Ten Blocks to Subtract Two Digit Numbers (With regrouping) exercise

Would you like to apply the knowledge you’ve learnt? You can review and practice it with the tasks for the video Using Base Ten Blocks to Subtract Two Digit Numbers (With regrouping).
• ### What are the steps to subtraction using regrouping?

Hints

What is the first step for subtracting using base ten blocks with regrouping?

Do you need to regroup from the tens place?

Solution
• Represent the number you started with on the place value chart using base ten blocks.
• Regroup from the tens place.
• Subtract 8 groups of ones from the ones place.
• Subtract 3 groups of tens from the tens place.
• Write the answer.
• 64 - 38 = 26
• ### How many ducks?

Hints

How many groups of tens are there?

Add on the ones.

In the image below:

• There are 3 tens and 4 ones.
• The number represented is 34.

Solution
1. There are 4 tens and 2 ones so the number represented is 42.
2. There are 6 tens and 5 ones so the number represented is 65.
3. There are 5 tens and 9 ones so the number represented is 59.
4. There are 7 tens and 6 ones so the number represented is 76.
• ### Counting ducks.

Hints

Use the place value chart and base ten blocks to help you. Do you need to regroup from the tens place?

Regroup a ten from the tens place and break it into 10 ones in the ones place. Now there are 7 tens and 13 ones.

Take 7 ones from the ones place. How many ones are left?

Subtract one ten from the tens place. How many tens are left after one was regrouped and one was subtracted?

Solution

83 - 17 = 66

• Regroup a ten from the tens place and break it into 10 ones in the ones place. Now there are 7 tens and 13 ones.
• Take 7 ones from the ones place.
• You have 6 ones left.
• Subtract one group of ten.
• Now, you have 6 tens and 6 ones.
• 6 tens and 6 ones is 66.
• ### Mr. Squeaks miscounted the ducks!

Hints

Do you need to regroup from the tens place?

After regrouping 1 ten to 10 ones, what is the next step?

Solution

66 - 28 = 38

• Regroup a ten from the tens place and break it into 10 ones in the ones place. Now there are 5 tens and 16 ones.
• Take 8 ones from the ones place.
• You have 8 ones left.
• Subtract two tens from the tens place.
• Now, you have 3 tens and 8 ones.
• 3 tens and 8 ones is 38.
• ### Rubber duck race mishap.

Hints
• One ten has been regrouped so there are now 13 ones.
• Take 5 ones from the ones place.
• How many ones are left?
• One ten has been regrouped so there are only five tens to subtract from.
• Subtract 2 more tens.
• How many tens and how many ones are left?
Solution

63 - 25 = 38

• Regroup a ten from the tens place and break it into 10 ones in the ones place. Now there are 5 tens and 13 ones.
• Take 5 ones from the ones place.
• You have 8 ones left.
• Subtract two more tens.
• Now, you have 3 tens and 8 ones.
• 3 tens and 8 ones is 38.
• ### How many ducks does Mr. Squeaks have?

Hints

Do you need to regroup a ten?

How many ones are left?

How many tens are left?

Solution

Problem 1

• 96 - 17 = 79
• There are 9 tens and 6 ones.
• Regroup a ten and break it up into 10 ones.
• You have 8 tens and 16 ones.
• Subtract 7 ones.
• You have 9 ones left.
• Subtract 1 ten.
• You have 7 tens left.
• 7 tens and 9 ones is 79.
Problem 2
• 54 - 36 = 18
• There are 5 tens and 4 ones.
• Regroup a ten and break it up into 10 ones.
• You have 4 tens and 14 ones.
• Subtract 6 ones.
• You have 8 ones left.
• Subtract 3 tens.
• You have 1 ten left.
• 1 ten and 8 ones is 18.
Problem 3
• 76 - 28 = 48
• There are 7 tens and 6 ones.
• Regroup a ten and break it up into 10 ones.
• You have 6 tens and 16 ones.
• Subtract 8 ones.
• You have 8 ones left.
• Subtract 2 tens.
• You have 4 tens left.
• 4 tens and 8 ones is 48.
Problem 4
• 95 - 47 = 48
• There are 9 tens and 5 ones.
• Regroup a ten and break it up into 10 ones.
• You have 8 tens and 15 ones.
• Subtract 7 ones.
• You have 8 ones left.
• Subtract 4 tens.
• You have 4 tens left.
• 4 tens and 8 ones is 48.