Download Algebra • Break Apart Numbers to Subtract Lesson 5.2

Lesson 5.2
Name
Algebra • Break Apart Numbers
to Subtract
Number and Operations
in Base Ten—2.NBT.B.5
MATHEMATICAL PRACTICES
MP1, MP5, MP6
Essential Question How does breaking apart a number
make subtracting easier?
Listen
Listen and
and Draw
Draw
Draw jumps on the number line to show how to
break apart the number to subtract.
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50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80
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40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70
Math
Talk
FOR THE TEACHER • Read the following problem.
Have children draw jumps on the number line to solve.
Mrs. Hill had 45 paintbrushes. She gave 9 paintbrushes
to students in her art class. How many paintbrushes
does Mrs. Hill have now? Repeat the same problem
situation for 72 − 7 and 53 − 6.
Chapter 5
MATHEMATICAL PRACTICES 6
Describe a Method
For one of the problems,
describe what you did.
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323
Model
Model and
and Draw
Draw
Break apart the number you are subtracting
into tens and ones.
Subtract 10.
Next, subtract 2 to get to 60.
Then subtract 5 more.
72 − 17 = ■
10
2
10 + 2 + 5 = 17
-5
7
-2
5
-10
50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80
So, 72 −
17 =
Share
hhow
Share and
and Show
Sh
—.
MATH
M
BOARD
B
Break apart the number you are subtracting.
Write the difference.
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43 − 18 =
10
45 − 14 =
10
—
4
5
46 − 17 =
324
2.
8
3
3.
—
—
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4.
44 − 16 =
—
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1.
Name
On
On Your
Your Own
Own
Break apart the number you are subtracting.
Write the difference.
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5.
57 − 15 =
—
6.
63 − 17 =
—
7.
68 − 19 =
—
8.
61 − 18 =
—
9.
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10.
SMARTER
Jane has 53 toys
in a box. She takes some
toys out. Now there are
36 toys in the box. How
many toys did Jane
take out of the box?
DEEPER
Look at Tom’s steps to solve
a problem. Solve this problem in the
same way.
42 − 15 = ?
— toys
Tom
35 – 18 = ?
35 – 10 = 25
25 – 5 = 20
20 – 3 = 17
Chapter 5 • Lesson 2
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325
MATHEMATICAL PRACTICES 8E8CPQ<›CFFB=FIJKIL:KLI<›GI<:@J@FE
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Math
11. 38 people are in the library.
Then 33 more people go into
the library. How many people
are in the library now?
— people
12.
MATHEMATICAL
PRACTICE
1
Analyze Alex
has 24 toys in a chest. He
takes some toys out of the
chest. Then there are 16 toys
in the chest. How many
toys did he take out of
the chest?
13.
— toys
SMARTER
Gail has two piles of newspapers.
There are 32 papers in the first pile. There
are 19 papers in the second pile. How many
more papers are in the first pile than in the
second pile?
— more papers
TAKE HOME ACTIVITY • Ask your child to write
a subtraction story that uses 2-digit numbers.
326
three hundred twenty-six
© Houghton Mifflin Harcourt Publishing Company
Write or draw to explain how you
solved the problem.
Practice and Homework
Name
Algebra • Break Apar t Numbers
to Subtract
Lesson 5.2
COMMON CORE STANDARD—2.NBT.B.5
Use place value understanding and properties of
operations to add and subtract.
Break apart the number you are
subtracting. Write the difference.
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1.
81 − 14 = —
2.
84 2 16 = —
3.
77 − 14 = —
4.
83 2 19 = —
5.
81 − 17 = —
6.
88 2 13 = —
7.
84 − 19 = —
8.
86 2 18 = —
Problem
Problem Solving
Solving
Solve. Write or draw to explain.
9. Mr . Pearce bought 43 plants. He gave
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14 plants to his sister . How many
plants does Mr . Pearce have now?
— plants
10.
Math
Draw a number line
and show how to find the difference
for 36 – 17 using the break apart
method in this lesson.
Chapter 5
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327
Lesson Check
(2.NBT.B.5)
1. What is the difference?
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63 − 19 = —
Spiral Review
(2.OA.A.1, 2.OA.B.2, 2.NBT.B.6)
2. What is the sum?
14
+ 23
4. Write a related subtraction fact
for 6 + 8 = 14.
3. What is the sum?
8+7=—
5. John has
7 kites. Annie has
4 kites. How many kites do
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they have altogether?
— kites
328
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