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).
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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. |
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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.
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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 |
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tens
1 |
ones
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3 |
5 |
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2 |
7 |
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6 |
2 |
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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. |
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2. Circle ten ones to
make a new ten. Add the tens and ones in columns.
3. Add. If
you can make a new ten from the ones, regroup.
| a.
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4 2
+ 1 5
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b.
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2 7
+ 4 5
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c.
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6 5
+ 2 6
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d.
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8 3
+ 1 5
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e.
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3 4
+ 1 9
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| f.
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5 2
+ 4 1
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g.
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1 3
+ 4 4
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h.
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6 3
+ 2 7
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i.
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3 6
+ 5 1
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j.
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6 6
+ 2 9
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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. |
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4. Add. Regroup the
ones to make a new ten.
| a.
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3 4
1 9
+ 2 6
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b.
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1 5
2 7
+ 4 5
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c.
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1 3
2 7
+ 2 6
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d.
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2 6
4 2
+ 1 9
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e.
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3 4
2 1
+ 1 9
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5.
Show the additions on the number line by drawing lines that are that long.
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a.
13 + 9 + 11 = _____
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b. 27 +
16 = _____
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This lesson is taken from Maria Miller's book Math Mammoth Add & Subtract 2B, and posted at www.HomeschoolMath.net with permission from the author. Copyright © Maria Miller. The lesson addresses the following Common Core standard for 2nd grade: 2.NBT.5.
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