2-Digit Subtraction Without Regrouping Click to return to - PDF document

Slide 1 / 137 Slide 2 / 137 2nd Grade 2 Digit Addition and Subtraction 2015-12-03 www.njctl.org Slide 3 / 137 Table of Contents Presentation 2 click on a topic to go to that section Mentally adding and subtracting 10 and 100 Addition Subtraction Mixed Addition and Subtraction Practice Lab: Give and Take

Slide 4 / 137 Standards for Mathematical Practices 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. MP8 Look for and express regularity in repeated reasoning. Click on each standard to bring you to an example of how to meet this standard within the unit. Slide 5 / 137 click on a topic to go to that section Subtraction 2 Digit Subtraction without Regrouping 2 Digit Word Problems without Regrouping Regrouping with Base Ten Blocks Regrouping without Base Ten Blocks Subtraction Word Problems with Regrouping Subtraction Practice Click to return to main Table of Contents Slide 6 / 137 2-Digit Subtraction Without Regrouping Click to return to Subtraction Table of Contents

Slide 7 / 137 2 Digit Subtraction What number is shown? Slide 8 / 137 2 Digit Subtraction Now we want to subtract 14. When we subtract, we take away. ALWAYS start with the bigger number when you subtract. Slide 9 / 137 2 Digit Subtraction Just like when we added, you need to line up the two numbers. tens ones 2 7 - 1 4 The ones are stacked and so are the tens.

Slide 10 / 137 2 Digit Subtraction Next, subtract the ones by crossing them out. tens ones 2 7 - 1 4 How many are left? Slide 11 / 137 2 Digit Subtraction Next, cross out the tens. tens ones 2 7 1 4 - 3 How many are left? Slide 12 / 137 2 Digit Subtraction tens ones 2 7 1 4 - 1 3

Slide 13 / 137 2 Digit Subtraction What number is shown? Slide 14 / 137 2 Digit Subtraction Let's subtract 20 Our subtraction number model is: 32 - 20 = Slide 15 / 137 2 Digit Subtraction Rewriting it makes it easier to subtract. tens ones 3 2 - 2 0 What do we subtract first?

Slide 16 / 137 2 Digit Subtraction What is the next step? tens ones 3 2 - 2 0 2 Slide 17 / 137 2 Digit Subtraction tens ones 3 2 - 2 0 1 2 Slide 18 / 137 2 Digit Subtraction What do we do first? 85 - 62 If there is not a place value chart, it may help to draw a line between the tens and ones to keep them seperated.

Slide 19 / 137 2 Digit Subtraction Now what do we do? 85 - 62 3 Slide 20 / 137 2 Digit Subtraction What is the answer? 85 - 62 2 3 Slide 21 / 137 2 Digit Subtraction 76 - 26

Slide 22 / 137 2 Digit Subtraction What should we do to this subtraction problem to make it easier to answer? 68 - 24 = Slide 23 / 137 2 Digit Subtraction 68 - 24 Slide 24 / 137 2 Digit Subtraction Roll all 4 dice and then subtract the numbers. -

Slide 25 / 137 1 If you take away 70, is the answer 24? Yes No Slide 26 / 137 2 If you take 12 away from this number, is the difference 7? Yes No Slide 27 / 137 3 Take away 83. What is the difference?

Slide 28 / 137 4 Take 32 away from this number, what is the difference? Slide 29 / 137 5 What is the difference 67 - 47 = ? Slide 30 / 137

Slide 31 / 137 Slide 32 / 137 2 Digit Word Problems Without Regrouping Click to return to Table of Contents Slide 33 / 137 Word Problems There are 24 children in a play. 11 children dance. The other children sing. How many children sing?

Slide 34 / 137 Word Problems There are 24 children in a play. 11 children dance. The other children sing. How many children sing? How many singers? 11 dancers 24 children in all Slide 35 / 137 Word Problems To find the difference, subtract: 24 Remember: - 11 1. Subtract the ones 2. Subtract the tens Slide 36 / 137 Number Model 24 or 24 - 11 = 13 - 11 13 Where is the bigger number in each problem?

Slide 37 / 137 Word Problems There are 37 chairs at the play. There are 13 couches. How many more chairs than couches are there? How can we find the answer? Slide 38 / 137 Practice Zachary sold 28 tickets for the play. Patrick sold 15 tickets. How many more tickets did Zachary sell than Patrick? Slide 39 / 137 Practice On Friday, 49 people came to the play. On Saturday, 25 fewer people came. How many came on Saturday?

Slide 40 / 137 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 Slide 41 / 137 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 Slide 42 / 137 8 There are 34 geese and 24 ducks in a pond. How many more geese than ducks are there?

Slide 43 / 137 9 There are 41 seagulls on the beach. Then 30 fly away. How many are left? Slide 44 / 137 10 Henry has 45 stamps. He gives 13 to Julie. How many stamps does he have left? Quiz Slide 45 / 137

Slide 46 / 137 Slide 47 / 137 Regrouping with Base Ten Blocks Click to return to Subtraction Table of Contents Slide 48 / 137 Regrouping What number is shown?

Slide 49 / 137 Regrouping 33 - 8 = ? Now we want to subtract 8. What do we do first? Slide 50 / 137 Regrouping 33 We have to take 8 ones away, - 8 but we do not have enough. How can we get more ones without changing the total number? Slide 51 / 137 Regrouping 33 - 8 = Now you can subtract!!! Cross out the ones that you take away. What is the difference?

Slide 52 / 137 Regrouping 52 - 7 = ? What do we need to do? Slide 53 / 137 Regrouping Look at the problem below. Do you need to regroup? How do you know? 63 - 9 = ? Slide 54 / 137 Regrouping Look at the problem below. First, decide is you need to regroup. 41 - 5 = ?

Slide 55 / 137 Regrouping Look at the problem below. First, decide is you need to regroup. 83 - 2 = ? Slide 56 / 137 Regrouping Look at the problem below. First, decide is you need to regroup. 46 - 22 = ? Slide 57 / 137 Regrouping Look at the problem below. Draw base ten blocks to help you solve the problem. 35 - 7 = ?

Slide 58 / 137 Regrouping Look at the problem below. Draw base ten blocks to help you solve the problem. 11 - 3 = ? Slide 59 / 137 Regrouping How will you know if you have to regroup? Slide 60 / 137 11 Which TWO problems require you to regroup? A 57 - 3 = ? B 38 - 9 = ? C 13 - 5 = ? D 40 - 0 = ?

Slide 61 / 137 12 Do you need to regroup? 45 - 8 = ? Yes No Slide 62 / 137 13 Do you need to regroup? 67 - 8 = ? Yes No Slide 63 / 137 14 56 Use base ten blocks at your seat to help you - 8

Slide 64 / 137 15 93 Use base ten blocks at your seat to help you - 14 Slide 65 / 137 Slide 66 / 137

Slide 67 / 137 Regrouping without Base Ten Blocks Click to return to Subtraction Table of Contents Slide 68 / 137 Regrouping Look at the problem. What do we need to do first? tens ones 3 3 1 8 - Slide 69 / 137 Regrouping Before we subtract, we need to make sure the written problem matches the base ten blocks. tens ones 3 3 1 8 -

Slide 70 / 137 Regrouping Before we subtract, we need to make sure the written problem matches the base ten blocks. tens ones 2 13 3 3 1 8 - Slide 71 / 137 Regrouping Start with the ones. Can we take 7 away from 2? What do we need to do? tens ones 5 2 3 7 - Slide 72 / 137 Base Ten Blocks Let's Practice! tens ones 6 9 - 5 7

Slide 73 / 137 Base Ten Blocks Let's Practice! 70 - 35 = tens ones - Slide 74 / 137 No Blocks! How can we solve this problem without base ten blocks? tens ones 5 2 3 6 - Slide 75 / 137 No Blocks! Now let's subtract! tens ones 4 12 5 2 3 6 -

Slide 76 / 137 Practice tens ones 6 0 2 7 - Slide 77 / 137 Practice tens ones 9 4 7 8 - Slide 78 / 137 Regrouping 25 Remember! - 12 More on top? 74 No need to stop! 36 - More on the floor? Go next door! 81 Numbers the same? 61 - Zeros the name!

Slide 79 / 137 Click on the picture below for more practice on the National Library of Virtual Manipulatives site. Change the columns to 2 prior to starting Slide 80 / 137 16 85 - 37 48 Yes No Slide 81 / 137 17 94 - 25 = 71 Yes No

Slide 82 / 137 18 67 - 58 Slide 83 / 137 19 88 - 34 = Slide 84 / 137 20 42 - 7 =

Slide 85 / 137 21 34 - 26 Slide 86 / 137 Slide 87 / 137

Slide 88 / 137 Word Problems with Regrouping Click to return to Subtraction Table of Contents Slide 89 / 137 Word Problems There are 65 students on the playground. 47 are wearing sneakers. How many are not wearing sneakers? What do we have to do to find the answer? Slide 90 / 137 Regrouping tens ones 6 5 Is there "more on the floor?" 4 7 -

Slide 91 / 137 Regrouping tens ones 5 15 We can not take 7 away 6 5 from 5, so we have to regroup 1 ten as 10 4 7 - ones. What do we do now? Slide 92 / 137 Regrouping tens ones 5 15 6 5 4 7 - 8 What is the next step? Slide 93 / 137 Word Problems 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 do to find the answer?