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Regrouping in Addition - free lesson

This is a complete lesson with instruction and exercises about regrouping in addition with 2-digit numbers (aka carrying). It is meant for initial instruction on the topic in 2nd grade. First, students use visual models (base ten blocks) to group ten units together and to record the addition with numbers written under each other (in columns). Then they practice the procedure without the visuals.

On a different page on my site, you can make worksheets for regrouping in addition (for 2nd grade).




When adding 3 + 9, we can circle ten
little ones to form a ten. We write “1”
in the tens column.

There are two little ones left over, so
we write “2” in the ones column.

  tens ones
  3
+   9
1 2

With 35 + 8, we circle ten little ones
to make a ten. There already are three
tens, so in total we now have four tens.
So, we write “4” in the tens column.

There are three little cubes left over, so
we write “3” in the ones column.

   
  tens ones
3 5
+   8
4 3

1. Circle ten cubes to make a new ten. Count the tens, including the new one. Count the
    ones. Write the tens and ones in their own columns. You can also use manipulatives.

a.



    

  tens ones
3 3
+   9
   
b.

  tens ones
2 5
+   8
   
c.

    
  tens ones
3 8
+   9
   
d.

  

  tens ones
2 7
+   7
   
e.

 

  tens ones
3 6
+ 1 8
   
f.

  tens ones
2 5
+ 2 7
   


When we make a new ten from the ones, we
are regrouping. The ten ones get grouped
as a ten, and are counted with the other tens.

This is also called carrying to tens
Imagine someone “gathering” ten little

tens
1
ones
 
 3  5
+ 2 7
6 2
cubes in his lap and “carrying” them over into the tens column as 1 ten.

To show this new ten, write a little “1” in the tens column above the other numbers.
Then add in the tens-column as usual, adding the little “1” also.

2. Circle ten ones to make a new ten. Add the tens and ones in columns.

a. 

 

           
   
   
 
  tens
1
ones
 
1 3
+ 2 9
  2
b.

   

 
   

       
       

   
  tens
1
ones
 
2 4
+ 3 8
   
c.  

   

     
 

     
     
     

  
  tens
1
ones
 
3 5
+ 1 9
   
d. 

   

   
 
 

       
   

     
  tens
1
ones
 
2 4
+ 4 7
   
e.

       

   
 
 

 
     
     

    
f.

   

     
   
 

     
    

   
g.

      

   
     
  
 

   
   
 

            
h.

     

     
   
   
 

    
    
  

       


3. Add. If you can make a new ten from the ones, regroup.

a.
4  2
+  1  5

 
b.
2  7
+  4  5

 
c.
6  5
+  2  6

 
d.
8  3
+  1  5

 
e.
3  4
+  1  9

 
 
f.
5  2
+  4  1

 
g.
1  3
+  4  4

 
h.
6  3
+  2  7

 
i.
3  6
+  5  1

 
j.
6  6
+  2  9

 

 

We can add three numbers by writing them under each other.
This is not any more difficult than adding two numbers.

On the right, first add the ones. 2 + 7 + 5 = 14. You get a new
ten. So, regroup and write that new ten with the other tens.

In the tens, add 1 + 3 + 2 + 1 = 7.

 

  1  
3 2
2 7
+ 1 5
7 4
 

4. Add. Regroup the ones to make a new ten.

a.
3  4
1  9
+  2  6

 
b.
1  5
2  7
+  4  5

 
c.
1  3
2  7
+  2  6

 
d.
2  6
4  2
+  1  9

 
e.
3  4
2  1
+  1  9

 

5. Show the additions on the number line by drawing lines that are that long.

a.   13 + 9 + 11 = _____

b.   27 + 16 = _____




This lesson is taken from my book Math Mammoth Add & Subtract 2-B. It addresses the following Common Core Standard for 2nd grade: 2.NBT.5.

Math Mammoth Add & Subtract 2-B

A self-teaching worktext for 2nd grade that covers mental addition and subtraction with two-digit numbers, and regrouping in addition and subtraction (carrying & borrowing).

Download ($5.65). Also available as a printed copy.

=> Learn more and see the free samples!

See more topical Math Mammoth books



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