As part of common core, we give students many strategies to help them find the answer to 2 digit subtraction problems. I like how these 2 digit subtraction strategies give students choices on how they can solve a problem. They help build meaning and number sense within the operation.

But here’s the thing… They can be a lot! Sometimes our curriculum goes too fast for students and they don’t quite master them and end up confused. That is why I am sharing the way I teach these strategies and the activities I give to my students to help them get the practice they need.

Before we get started, for students to truly be successful with these strategies they need a solid foundation with math facts. If students have to take time to recall or figure out a math fact, it can get them confused for what they are doing with the 2 digit subtraction strategy.

So no worries, I’ve got something special for you. I’m sharing my 7 Steps to Ensure Math Fact Fluency in a free workbook for 1st and 2nd grade teachers. Download your free copy here.

Okay, let’s get started with the 2 digit subtraction strategies I teach in my classroom.

Hundreds Chart

First, we have students working with a hundred’s chart for them to solve 2 digit subtraction problems. For this strategy, I really need to make sure that students understand the patterns with the hundreds chart.

I want my students to know that if they go up on the hundred’s chart, they are subtracting by tens. They need to know if they go left on the hundred’s chart, they are subtracting by by ones.

When I have my students look at a 2 digit subtraction problem like 72-35, I first ask what number we start with on the hundred’s chart. They need to know with subtraction, we have to start with the bigger number.

Then I ask how many tens are in 35. Three tens. So we go up three rows on the hundreds chart. We still need to  take away the ones in 35. How many ones are in 35? There are 5 ones. So we go left 5 ones. We land on 37 so that is our answer.

I have students get lots of practice with this. It’s important that they have plenty of space on clean hundreds charts to not get confused. So I have them work on hundred chart worksheets and fun scoot activities. They can be used as centers or whole group activities. Find these Subtraction Hundreds Chart Activities here.

 

Open Number Line

With this 2 digit subtraction strategy, students make jumps back on a number line. They can also count on to subtract on a number line. This can be confusing to students at first, but if they have a good foundation with fact families, it makes sense that they can use addition to subtract. To learn more about fact families, read this blog post: 3 Reasons You Need To Teach Fact Families

For teaching this strategy, I draw a number line on the board and write an equation. Let’s use the example of 63-24. I show my students that if we are counting back on the number line, I will start by putting 63 on the right side.

Then I ask how many tens are in 24. There are 2 tens so I will make two jumps back and label them.

Next I ask how many ones are in 24. There are 4 ones so I will make 4 jumps back and label them. I landed on 39 so that is the answer.

Students really need a lot of practice with this strategy. I find it helpful when I give them enough space on a number line and remind them to leave spaces in between their numbers so they can actually read their writing.

I have my students practice with worksheets and scoot activities. Find the 2 Digit Subtraction Number Line Activities resource I use here.

 

Break Apart

This 2 digit subtraction strategy is often a favorite with my students. In this strategy, students break the number being subtracted into tens and ones. Then break apart the ones another time if needed to get down to the next tens to make it easy.

This takes some practice. I just start by having my students practice break apart the ones so that they can get to the next tens. For example, I may show them if we have 45-9, I’m going to break apart the 9 into 4 and 5. Then I can think about it as 45-5=40 and 40-4=36.

Then I’ll add the tens into it, like 45-19. They would just take away a ten first so it would look like 45-10=35. 35-5=30. 30-4=26.

I like to provide my students with worksheets that have boxes that help them think about breaking apart the number. Find the worksheets and other activities I give my students here.

Tens and Ones Chart

This strategy is the regular 2 digit subtraction algorithm. For students to truly understand the meaning behind the steps, we use models, draw pictures, and then just use numbers.

I like to show my students when we need to regroup. I often say something like, “If I have 5 ones, can I take away 8? Nope, I need to regroup.”

Find the worksheets and activities I use to help students answer 2 digit subtraction with regrouping here.

I hope that you have found many tips in helping students master these 2 digit subtraction strategies. It comes by teaching to build number sense and giving students a lot of practice. Find all of my 2 digit addition and subtraction strategies all in one bundle here.

For more on how to teach 2 digit addition strategies, read this blog post: 2 Digit Addition Strategies That Work

For extra help for getting students to fluently add and subtract 2 digit numbers, they need to be fluent in math facts 1-20. Download my free workbook for help: 7 Steps to Ensure Math Fact Fluency.

Download it here.