Break Apart Ones to Add

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Break Apart Ones to Add

Lesson 4.1 Reteach

Sometimes when you are adding, you can break apart ones to make a ten.

37 + 8 = _ ?

Look at the two-digit addend, 37. What digit

is in the ones place? _ 7

Decide how many you need to add to the ones digit to make 10.

7 + _ 3 = 10, and 37 + _ 3 = 40

Break apart that number from the one-digit addend, 8.

8 - 3 = 5

Finally, write the new number sentence. 40 + 5 = _ 45

Break apart ones to make a ten. Then add and write the sum.

1. 28 + 6 =

2. 34 + 7 =

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Use Compensation

Lesson 4.2 Reteach

This is a way to add 2-digit numbers. Take ones from one addend to make the other addend a tens number.

27 + 38 = _ ?

38 First, find the addend with the greater ones digit. _

How many ones would you need to add to make it a tens number?

38 + _ = 40

Add _ 2to make _ 40 .

Next, take that many ones away from the other addend.

27 - 2 = 25

The two new addends are _ 25and _ 40 .

Write the new addition sentence to find the sum.

_ 25 + _ 40 = _ 65

Show how to make one addend the next tens number. Complete the new addition sentence.

1. 28 + 16 = ? _ + _ = _

2. 37 + 24 = ?

_ + _ = _

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Break Apart Addends as Tens and Ones

Lesson 4.3 Reteach

25 + 46 = ?

Break apart 25 into tens and ones.

Break apart 46 into tens and ones.

25

+

46

20 + 5

+

40 + 6

Then, add the tens from the two addends._ 20 + _ 40 = _ 60

Add the ones from the two addends.

_ 5 + _ 6 = _ 11

Add the two sums._ 60 + _ 11 = _ 71 So, 25 + 46 = _ 71 .

Break apart the addends to find the sum.

1. 12 + 48 = ?

_ + _ + _ + _

Add the tens._ + _ = _

Add the ones. _ + _ = _

How many in all?_ + _ = _

So, 12 + 48 = _ .

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Model Regrouping for Addition

Lesson 4.4 Reteach

Add 18 and 25.

Show 18 and 25 with

.

13 Count the ones.

How many ones

are

there

in

all?_ ones

yes Can you make a ten?--

Trade 10 ones for 1 ten. This is called regrouping.

Tens

Ones

Tens

Ones

4 Count the tens. How many

tens are there in all?_ tens

3 Count the ones.

ones are there in

Halol?wma ny_ ones

_ 4 tens _ 3 ones is the same as _ 43 .

Tens

Ones

Write how many tens and ones in the sum. Write the sum.

1. Add 46 and 19. 2. Add 45 and 27. 3. Add 58 and 38.

Tens

Ones

Tens

Ones

Tens

Ones

_ tens _ ones

_

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_ tens _ ones

_

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_ tens _ ones _

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Model and Record 2-Digit Addition

Lesson 4.5 Reteach

Model 33 + 19.

Tens

Ones

Tens Ones

Haroewthmearenyinoanlle?s_ 1_ 2ones yes Can you make a ten?--

B

33 1 9

Regroup 10 ones as 1 ten.

Tens

Write a 1 in the tens column

to show the regrouped ten.

2 How

after

mreagnroyuopninegs?areleft_ ones

Write that number in the ones place.

Haroewthmearenyinteanll?s_ 5tens

Tens

Write that number in the tens place.

Ones

Tens Ones

B1

33

1 9

2

Ones

Tens Ones

B1

33 1 9

52

Draw quick pictures to help you solve. Write the sum.

1. Tens Ones

Tens

Ones

2.

Tens Ones

Tens

Ones

B

B

47 2 5

36 14 6

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2-Digit Addition

Lesson 4.6 Reteach

Add 27 and 36.

STEP 1

Show 27 and 36. Add the ones.

7 + 6 = 13

Tens

Ones

STEP 2

If you can make a 10, regroup 10 ones for 1 ten.

13 ones =1 ten 3 ones

Tens

Ones

STEP 3

Add the tens. Remember to add the regrouped ten.

1 + 2 + 3 = 6

Tens

Ones

Tens Ones

B

27 3 6

Tens Ones

B1

27 3 6

3

Tens Ones

B1

27 3 6

63

Regroup if you need to. Write the sum.

1. Tens Ones

B

2. Tens Ones

B

3. Tens Ones

B

54 2 9

17 6 1

41 2 9

4. Tens Ones

B

35 3 2

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Practice 2-Digit Addition

Lesson 4.7 Reteach

Eliza sold 47 pencils in one week. She sold 65 pencils the next week. How many pencils did she sell in both weeks?

Add 47 and 65.

Regroup.

Add the ones.

12 ones = 1 ten and 2 ones

7 + 5 = 12

B4 7

B1 4 7

+___6___5__

_+___6___5_

2

Add the tens.

1 + 4 + 6 = 11

B1 4 7

+___6___5__

11 2

Write the sum.

B 1.

4 3 +_ 6 9

B 2.

7 6 +_ 5 8

B 3.

3 8 +_ 4 2

B 4.

8 5 +_ 6 8

B 5.

8 2 +_ 4 7

B 6.

8 1 _ + 1 7

B 7.

2 7 +_ 8 6

B 8.

5 1 +_ 3 8

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Rewrite 2-Digit Addition

Lesson 4.8 Reteach

Add. 43 + 19 = ?

STEP 1

STEP 2

STEP 3

What is the tens digit in

43?_ 4

What is the tens digit in

19?_ 1

Add the ones. Regroup if you

Write 4 in the

Write 1 in the

need to.

tens column.

tens column.

Add the tens.

Write the ones digit, 3, Write the ones digit, 9,

in the ones column.

in the ones column.

Tens Ones

B

43

Tens Ones

B

43

1 9

Tens Ones

B1

43 1 9

62

Rewrite the numbers. Then add.

1. 26 + 9

2. 16 + 43 3. 32 + 38 4. 23 + 26

B B B B

+________

+___ _____

+___ _____

+___ _____

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