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2nd Grade

2 Digit Addition and Subtraction

2015-12-03

www.njctl.org

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click on a topic to go to that section

Table of ContentsPresentation 2

Addition

Subtraction

Mixed Addition and Subtraction Practice

Mentally adding and subtracting 10 and 100

Lab: Give and Take

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Standards for Mathematical Practices

MP8 Look for and express regularity in repeated reasoning.

MP1 Make sense of problems and persevere in solving them.

MP2 Reason abstractly and quantitatively.

MP3 Construct viable arguments and critique the reasoning of others.

MP4 Model with mathematics.

MP5 Use appropriate tools strategically.

MP6 Attend to precision.

MP7 Look for and make use of structure.

Click on each standard to bring you to an example of how to meet

this standard within the unit.

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topic to go to that section

Subtraction

2 Digit Subtraction without Regrouping

Regrouping with Base Ten Blocks

Subtraction Word Problems with Regrouping

Subtraction Practice

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2 Digit Word Problems without Regrouping

Regrouping without Base Ten Blocks

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2-Digit SubtractionWithout Regrouping

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What number is shown?

2 Digit Subtraction

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Now we want to subtract 14.

When we subtract, we take away.ALWAYS start with the bigger number when you subtract.

2 Digit Subtraction

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tens ones

2 71 4-

Just like when we added, you need to line up the two numbers.

2 Digit Subtraction

The ones are stacked and so are the tens.

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tens ones

2 71 4-

Next, subtract the ones by crossing them out.

How many are left?

2 Digit Subtraction

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tens ones

2 71 4-

Next, cross out the tens.

How many are left?

3

2 Digit Subtraction

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tens ones

2 71 4-

31

2 Digit Subtraction

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What number is shown?

2 Digit Subtraction

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Let's subtract 20Our subtraction number model is:

32 - 20 =

2 Digit Subtraction

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tens ones

3 22 0-

Rewriting it makes it easier to subtract.

2 Digit Subtraction

What do we subtract first?

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tens ones

3 22 0-

2

What is the next step?

2 Digit Subtraction

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tens ones

3 22 0-

21

2 Digit SubtractionSlide 18 / 137

8562-

What do we do first?

2 Digit Subtraction

If there is not a place value chart, it may help to draw a line between the tens and ones to keep them seperated.

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Now what do we do?

3

2 Digit Subtraction

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What is the answer?

32

2 Digit Subtraction

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76- 26

2 Digit Subtraction

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68 - 24 =

What should we do to this subtraction problem to make it easier to answer?

2 Digit Subtraction

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68 - 24

2 Digit Subtraction

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-Roll all 4 dice and then subtract the numbers.

2 Digit Subtraction

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1 If you take away 70, is the answer 24?

Yes

No

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2 If you take 12 away from this number, is the difference 7?

Yes

No

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3 Take away 83. What is the difference?

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4 Take 32 away from this number, what is the difference?

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5 What is the difference 67 - 47 = ?

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2 Digit Word Problems Without Regrouping

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There are 24 children in a play. 11 children dance.The other children sing. How many children sing?

Word Problems

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How many singers?

24 children in all

There are 24 children in a play. 11 children dance.The other children sing. How many children sing?

11 dancers

Word Problems

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To find the difference, subtract:

24- 11

Remember:

1. Subtract the ones2. Subtract the tens

Word Problems

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Number Model

24 - 11 = 13 or 24- 11

13

Where is the bigger number in each problem?

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How can we find the answer?

There are 37 chairs at the play. There are 13 couches.

How many more chairs than couches are there?

Word Problems

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Zachary sold 28 tickets for the play.Patrick sold 15 tickets. How many

more tickets did Zachary sell than Patrick?

Practice

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On Friday, 49 people came to the play. OnSaturday, 25 fewer people came. How many

came on Saturday?

Practice

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6 There are 28 girls and 16 boys in the class. How many more girls than boys are in the class?

A 12

B 14

C 36

D 46

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7 Britney sold 39 boxes of popcorn and 18 sodas. How many more boxes of popcorn than sodas did she sell?

A 11

B 18

C 21

D 26

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8 There are 34 geese and 24 ducks in a pond. How many more geese than ducks are there?

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9 There are 41 seagulls on the beach. Then 30 fly away. How many are left?

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10 Henry has 45 stamps. He gives 13 to Julie. How many stamps does he have left?

Quiz

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Regroupingwith Base Ten Blocks

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What number is shown?

Regrouping

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33 - 8 = ?Now we want to subtract 8.

What do we do first?

Regrouping

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How can we get more ones without changing the total

number?

We have to take 8 ones away, but we do not have enough.

33 8-

Regrouping

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33 - 8 = Now you can subtract!!!

Cross out the ones that you take away.

Regrouping

What is the difference?

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52 - 7 = ?What do we need to do?

Regrouping

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Look at the problem below. Do you need to regroup? How do you know?

63 - 9 = ?

Regrouping

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Look at the problem below. First, decide is you need to regroup.

41 - 5 = ?

Regrouping

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Look at the problem below. First, decide is you need to regroup.

83 - 2 = ?

Regrouping

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Look at the problem below. First, decide is you need to regroup.

46 - 22 = ?

Regrouping

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Look at the problem below. Draw base ten blocks to help you

solve the problem.

35 - 7 = ?

Regrouping

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Look at the problem below. Draw base ten blocks to help you

solve the problem.

11 - 3 = ?

Regrouping

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How will you know if you have to regroup?

Regrouping

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11 Which TWO problems require you to regroup?

A 57 - 3 = ?

B 38 - 9 = ?

C 13 - 5 = ?

D 40 - 0 = ?

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12 Do you need to regroup?

45 - 8 = ?

Yes

No

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13 Do you need to regroup?

67 - 8 = ?

Yes

No

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14

56

- 8Use base ten blocks at your seat to help you

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15

93

- 14Use base ten blocks at your seat to help you

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Regroupingwithout Base Ten Blocks

Click to return to SubtractionTable of Contents

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tens ones

3 31 8-

Regrouping

Look at the problem. What do we need to do first?

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tens ones

3 31 8-

RegroupingBefore we subtract, we need to make sure the written problem matches the

base ten blocks.

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tens ones

3 31 8-

RegroupingBefore we subtract, we need to make sure the written problem matches the

base ten blocks.

2 13

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tens ones

5 23 7-

Start with the ones.Can we take 7 away from 2?

What do we need to do?

Regrouping

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Let's Practice!

tens ones

-6 9

75

Base Ten Blocks

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Let's Practice!

tens ones

-

Base Ten Blocks

70 - 35 =

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No Blocks!

How can we solve this problem without base ten blocks?

5 2 3 6-

tens ones

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No Blocks!

Now let's subtract!

5 2 3 6-

tens ones

124

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Practice

6 0 2 7-

tens ones

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Practice

9 47 8-

tens ones

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2512-

-7436

Remember!

More on top?No need to stop!

More on the floor?Go next door!

Numbers the same?Zeros the name! -

8161

Regrouping

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Change the columns to 2 prior to starting

Click on the picture below for more practice on the National Library of Virtual Manipulatives site.

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16 85- 37 48

Yes

No

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17 94 - 25 = 71

Yes

No

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18 67- 58

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19 88 - 34 =

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20 42 - 7 =

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21 34- 26

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Word Problems with Regrouping

Click to return to SubtractionTable of Contents

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What do we have to doto find the answer?

There are 65 students on the playground.47 are wearing sneakers. How many are

not wearing sneakers?

Word Problems

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tens ones

6 5 4 7-

Is there "more on the floor?"

Regrouping

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tens ones

6 5 4 7-

We can not take 7 awayfrom 5, so we have to regroup 1 ten as 10

ones.

What do we do now?

155

Regrouping

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tens ones

6 5 4 7-

155

8

Regrouping

What is the next step?

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One day 45 cars and 19 trucks were washed at the car wash. How many more cars than trucks were washed?

What do we have to doto find the answer?

Word Problems

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How do I subtract?

4 5 1 9

Regrouping

tens ones

-

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There are 83 students eating lunch. 55 are eating hot lunch. How manystudents are not eating hot lunch?

Word Problems

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A soda cost 75 cents. Mr. Westhas 46 cents. How many more cents does he need for a soda?

Word Problems

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22 There are 50 students in the library. 27 of them are wearing blue. How many are not wearing blue?

A 33

B 37

C 23

D 77

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23 Colin had 32 baseball cards. He sold 16. How many were left?

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24 Megan had 73 books at the yard sale. She sold 42. How many are left?

A 31

B 115

C 211

D 35

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25 The pet store has 58 fish. They sell 39 fish. How many fish are left at the pet store?

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26 In art class, Jeff made 61 paper moons. Kelly made 9. How many more moons did Jeff make?

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Subtraction Practice

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How can we write this problem to find the difference?

There are 84 apples on theapple tree. Sara picks 68

apples. How many apples are left on the tree?

Word Problems

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8468-

YES!Do we have to regroup?

There is more on the floor.

Regroup 1 ten for 10 ones

Subtract the ones first,then the tens.

How do you know?

What do we do first?

What do we do next?

Click each box tocheck your answer

Practice

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NO!Do we have to regroup?

There is more on top.

Subtract the ones.

Subtract the tens.

How do you know?

What do we do first?

What do we do next?

Click each box tocheck your answer

Review

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Jenna picks up 34 sea shells.She puts 17 of them in a box.

How many does she have left?

Word Problems

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Sadie buys 74 pieces of paper.She uses 44 for her book.

How many pieces of paper are left?

Word Problems

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27 Mom bakes 23 cupcakes. She decorates 19 purple and the rest blue. How many were blue?

A 16

B 4

C 14

D 34

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28 Becky buys 57 apples and oranges. 23 are oranges. How many are apples?

A 23

B 53

C 57

D 34

Pick the correct answer from each column to complete the subtraction sentence for this word problem.

_______ - _______ = 34

E 23

F 53

G 57

H 34

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29 Kira can jump a rope 94 times. Myah can jump a rope 79 times. How many more times can Kira jump than Myah?

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30 The team scored 74 points. Shawn scored 36 of the points. How many points did the rest of the team score?

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31 There are 49 markers in the box. 14 of them are being used. How many are left in the box?

Quiz

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Mixed Practice

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There are 78 people wearing blue hats and 35 people wearing red

hats. How many hats in all?

Addition

The question askshow many in all

Line up our numbers to add

Is this an addition or subtraction problem?

How do we know?

What do we have todo to find the answer?

Word Problems

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What do we add first?

Practice

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8 + 5 = Now what do we do?

Practice

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Now what do we do?

3

1

Practice

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7835+

3

11 + 7 + 3 =

Practice

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7835+

311

1

Practice

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The paint store has 64 cans of paint. They sell 55 cans. How

many cans are left?

SubtractionIs this an addition or subtraction problem?

The problem talks about takingaway and asks how many are left.How do we know?

Line up the numbers,with the biggest number

on top to subtract.

What do we have todo to find the answer?

Click each boxto check the

answer

Practice

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6455-

Practice

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Practice

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What clue words tell us what kind of problem this is?

There are 50 blue birds and 86 red birds.How many birds are there all together?

Practice

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Two boys collected a total of 43 rocks. If John collected 22, how

many did Dave collect?

Practice

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32 Kurt has 70 pennies. He gives Jay 48 pennies. How many pennies does he have left?

A 38

B 22

C 118

D 32

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33 Jenny does 29 jumping jacks. Nicole does 33 jumping jacks. How many jumping jacks did they do all together?

A 52

B 16

C 62

D 4

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34 There are 56 yellow flowers and 53 red flowers. How many flowers in all?

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35 There are 38 kids that have brown eyes and 27 kids that have blue eyes. How many more kids have brown eyes?

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36 Jack has to drive 82 miles. He already drove 47 miles. How many more miles does Jack have to drive?

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Lab: Give and Take

Practice regrouping/ trading “tens” and “ones” while playing this game

Click here for complete directions

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