Teaching 3 Digit Subtraction Strategies | 4 Effective Ways to Teach Regrouping

If you’re a 2nd grade teacher, you know how challenging teaching 3 digit subtraction can be. In order for students to be successful with this skill, they must have a strong foundational understanding of place value in order to master regrouping. In this blog post, I’m breaking down 4 effective 3 digit subtraction strategies and sharing some of my favorite regrouping activities to help make your lessons go smoothly!

Teaching 3 Digit Subtraction With Regrouping

Before introducing 3 digit subtraction with regrouping, it’s essential that your students have a strong base knowledge of place value. Without it, they’ll be lost and confused! I truly believe you can’t practice and reinforce place value enough in the lower elementary grades, because it’s the foundation for so many key concepts, like regrouping. 

Begin by first introducing subtraction with regrouping strategies with 2 digit numbers. You can read more about how I do this using anchor charts and other activities in this blog post. 

The progression of skills should look like this: place value→ 2 digit subtraction with regrouping → 3 digit subtraction with regrouping.

Looking for a fun way to practice and reinforce place value throughout the year? Grab this FREE Place Value Boxes activity by filling out the form below.

3 Digit Subtraction Strategies

There are 4 key 3 digit subtraction strategies that I teach when tackling the concept of regrouping. For the most part, these are the same as those for 2 digit subtraction with regrouping. Read on to learn how to teach these 3 digit subtraction strategies to your students using hands-on activities.

#1: Base Ten Strategy

If you’ve been around for a while, you know how much I love beginning any concept or unit with a concrete, hands-on strategy, which is why I always teach the base ten strategy first. This strategy is rooted in place value and provides students a hands-on and visual way to see this strategy in action. 

I like using a variety of base ten manipulatives, such as base ten blocks, craft supplies (think, paper squares, pipe cleaners, pom pom balls), as well as snacks (like cheese crackers, pretzel rods, and marshmallows). Check out more of my favorite math manipulatives and tools for teaching regrouping in this blog post. 

Place Value Subtraction Work Mat

I always introduce the 3 digit subtraction with regrouping base ten strategy with a hands-on Place Value Subtraction Work Mat. Students can practice a variety of examples using this concrete activity. 

In this example, students solve for 323-105. They begin by building the minuend (the number from which to be subtracted from). In this case, the minuend is 323. 

Then, they subtract the ones place first. Since you can’t subtract 5 from 3, they must regroup. They exchange a tens block for ten ones. 

Then they can subtract the ones to get 8. Next, they subtract the tens. There is now only 1 ten, so 1-0=1 in the tens place. Finally, they subtract the hundreds. 3-1=2 in the hundreds place. Therefore, the final difference is 218.

#2: Number Line Strategy

The next of the 3 digit subtraction strategies is the open number line strategy. Open number lines are a great visual strategy for students to model subtraction using giant hops to represent the hundreds place, large hops for the tens, and small hops for the ones. 

This strategy helps students visualize each place value as they subtract to help them understand WHY they end on the answer they do.

Subtracting on a Number Line Work Mat

This Subtracting on a Number Line Work Mat is a great way for students to practice multiple 3 digit subtraction with regrouping problems. I like to use this activity during whole group instruction so we can work through examples together with me modeling on the board. 

In this example, students will solve for 453-127.

1. They’ll begin by writing the minuend (in this case, 453) at the end of the number line.
2. Then, they’ll make 1 giant leap backwards to represent the hundreds place, 2 large hops to represent the tens, and 7 small hops to represent the ones.
3. This will lead them to the final difference of 326.

Subtracting 3 Digit Numbers On an Open Number Line Worksheet

After students practice subtracting 3 digit numbers on a number line, I like to have them practice different examples by using some sort of subtraction with regrouping worksheet.

This activity also helps them think through the process to better understand the why by answering questions about which number goes at the end of the number line, how many giant hundreds leaps they made, how many large tens hops, and how many small ones hops.

#3: Subtracting Across Zeroes

3 digit subtraction gets really tricky when zeroes are involved. If students need to regroup but there is a 0 in the ones or tens place, they must borrow from the next place value. In the subtracting across zeroes strategy, students are taught to ZAP those zeroes, get rid of them, and keep regrouping. See how this is done in the following example!

Zapping Those Zeroes

With this Zapping Those Zeroes activity, students will work to ZAP the zeroes and eliminate them so they can regroup and subtract. In the example of 307-299, students need to regroup to solve for the ones place.

They look at the hundreds place and ask, “how many tens are in 300?” Since there are 30 tens, they will take one ten away, making the value of the tens 29 and the value of the ones 17. Then, they can subtract the ones to get 8 and subtract the tens to get 0.

#4: Standard Model Strategy

The final 3 digit subtraction with regrouping strategy is the standard model. This is the last strategy I recommend teaching, even if it’s the first (and maybe only!) strategy you learned as a kid. 

I like to use the saying, “More on the floor? Go next door and get ten more! More on top? No need to stop! Numbers the same? Zeroes the game!”

See how this is done in the activity below.

Subtraction with Regrouping Practice Activity

In this Subtraction with Regrouping practice activity, students will solve various 3 digit subtraction problems using the standard model. I like to have students highlight the ones place so they know where to begin. 

In the first example below, you’ll find 261-134.

They’ll go through the process of subtracting, beginning in the ones place, using the saying above. They will see that they cannot subtract 4 from 1, therefore, they need to regroup a ten. To do this, they need to do the following steps:

1. Cross out the 1 in the ones place and the 6 in the tens place. We are going to regroup 10 from 60 (the 6) and add it to the 1 in the ones place to make 11.
2. Replace the 6 with a 5 (make sure to remind them that the value represents 50). Replace the 1 with an 11. Explain that we regrouped 10 from the tens place and added ten to the ones place to make 11.
3. Now they can subtract starting with the ones to solve for the difference.

I hope this blog post has helped you feel more confident in teaching 3 digit subtraction with regrouping and given you some effective and hands-on activities to use to teach these 3 digit subtraction strategies to your students.

Remember, every student’s brain works differently, and the strategy that clicks for one student may not with the next. That’s why teaching each strategy is key, as it empowers your students to use the strategy that works best for their learning style!

Are you looking for more 3 digit subtraction activities and lesson plans? Check out these resources and blog posts below! You can also browse my TPT store for more regrouping resources.

• 2 Digit Subtraction with Regrouping Strategies
• Math Manipulatives and Tools for Teaching Addition and Subtraction with Regrouping