Chapter 2 Addition Click the mouse or press the space bar to continue.

Chapter 2 Addition Click the mouse or press the space bar to continue.
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Lesson 2-1 Addition Properties
Lesson 2-2 Problem-Solving Skill: Estimate or Exact Answer Lesson 2-3 Estimate Sums Lesson 2-4 Two-Digit Addition Lesson 2-5 Add Money Lesson 2-6 Problem-Solving Investigation: Choose a Strategy Lesson 2-7 Three-Digit Addition Lesson 2-8 Add Greater Numbers Chapter Menu

Five-Minute Check (over Chapter 1) Main Idea and Vocabulary
2-1 Addition Properties Five-Minute Check (over Chapter 1) Main Idea and Vocabulary California Standards Key Concept: Properties Example 1: Use Properties to Add Example 2: Associative Property Lesson 1 Menu

I will use addition properties to add whole numbers.
2-1 Addition Properties I will use addition properties to add whole numbers. Commutative Property of Addition Identity Property of Addition Associative Property of Addition Lesson 1 MI/Vocab

2-1 Addition Properties Standard 3NS2.1 Find the sum or difference of two whole numbers between 0 and 10,000. Standard 3AF1.1 Represent relationships of quantities in the form of mathematical expressions, equations, or inequalities. Lesson 1 Standard

2-1 Addition Properties Lesson 1 Key Concept 1

Find the sum. Identify the property.
2-1 Addition Properties Find the sum. Identify the property. 7 + 5 = and = Lesson 1 Ex1

2-1 Addition Properties Answer: The sum is 12. The order in which the numbers are added does not change the sum. This is the Commutative Property of Addition. Lesson 1 Ex1

Which property is shown here? 4 + 3 = 3 + 4
2-1 Addition Properties Which property is shown here? = 3 + 4 Identity Property of Addition Commutative Property of Addition Associative Property of Addition Additive Property Lesson 1 CYP1

Answer: So, Jon has 15 writing utensils in all.
2-1 Addition Properties Jon has 7 pencils, 5 pens, and 3 highlighters. How many writing utensils does Jon have? = = 5 + (7 + 3) = = 15 Answer: So, Jon has 15 writing utensils in all. Lesson 1 Ex2

2-1 Addition Properties Monica has 3 red crayons, 6 blue crayons, and 7 purple crayons. How many crayons does Monica have in all? 15 crayons 16 crayons 17 crayons 18 crayons Lesson 1 CYP2

End of Lesson 1

Five-Minute Check (over Lesson 2-1) Main Idea California Standards
2-2 Problem-Solving Skill: Estimate or Exact Answer Five-Minute Check (over Lesson 2-1) Main Idea California Standards Example 1: Problem-Solving Skill Lesson 2 Menu

2-2 Problem-Solving Skill: Estimate or Exact Answer I will decide whether an estimate or an exact answer is needed to solve a problem. Lesson 2 MI/Vocab

2-2 Problem-Solving Skill: Estimate or Exact Answer Standard 3MR2.5 Indicate the relative advantages of exact and approximate solutions to problems and give answers to a specified degree of accuracy. Standard 3NS2.1 Find the sum or difference of two whole numbers between 0 and 10,000. Lesson 2 Standard 1

2-2 Problem-Solving Skill: Estimate or Exact Answer To celebrate Arbor Day, a town planted trees one weekend. On Saturday, 53 trees were planted. Another 38 trees were planted on Sunday. About how many trees were planted in all? Lesson 2 Ex1

Understand What facts do you know? On Saturday, 53 trees were planted.
2-2 Problem-Solving Skill: Estimate or Exact Answer Understand What facts do you know? On Saturday, 53 trees were planted. On Sunday, 38 trees were planted. What do you need to find? Find about how many trees were planted in all. Lesson 2 Ex1

2-2 Problem-Solving Skill: Estimate or Exact Answer Plan You need to decide whether to estimate or find an exact answer. Since the question asks about how many trees were planted, you need to estimate. Lesson 2 Ex1

2-2 Problem-Solving Skill: Estimate or Exact Answer Solve First, find about how many trees were planted each day. Estimate by rounding to the closest ten. Lesson 2 Ex1

2-2 Problem-Solving Skill: Estimate or Exact Answer Solve Then, add. 50 + 40 90 Answer: So, about 90 trees were planted in all. Lesson 2 Ex1

2-2 Problem-Solving Skill: Estimate or Exact Answer Check Look back at the problem. If the question asked for an exact answer you would find = 91. The estimate is close to the exact answer. So, the estimate makes sense. Lesson 2 Ex1

End of Lesson 2

Five-Minute Check (over Lesson 2-2) Main Idea and Vocabulary
2-3 Estimate Sums Five-Minute Check (over Lesson 2-2) Main Idea and Vocabulary California Standards Example 1: Estimate by Rounding Example 2: Estimate by Rounding Example 3: Estimate by Rounding Lesson 3 Menu

I will estimate sums using rounding and front-end estimation.
2-3 Estimate Sums I will estimate sums using rounding and front-end estimation. estimate front-end estimation Lesson 3 MI/Vocab

2-3 Estimate Sums Standard 3NS1.4 Round off numbers to 10,000 to the nearest ten, hundred, and thousand. Standard 3MR2.5 Indicate the relative advantages of exact and approximate solutions to problems and give answers to a specified degree of accuracy. Lesson 3 Standard 1

Step 1 Round each number to the nearest ten.
2-3 Estimate Sums Kevin found 14 snails in his backyard after a rain. The next day he found 28 more snails. About how many snails did he find in all? To find the total, find Since the question says about how many people, estimate Step 1 Round each number to the nearest ten. Lesson 3 Ex1

Answer: So, Kevin found about 40 snails in all.
2-3 Estimate Sums Step 2 Add. 14 28 + 10 30 + 40 Answer: So, Kevin found about 40 snails in all. Lesson 3 Ex1

2-3 Estimate Sums Joyce invited 16 girls to her birthday party. She invited 11 boys. About how many people did she invite to her birthday party in all? 27 people 35 people 20 people 30 people Lesson 3 CYP1

Answer: So, Samir rode his bike about 70 miles.
2-3 Estimate Sums Samir rode his bike 28 miles on Monday and 43 miles on Tuesday. Estimate how many miles he rode on those two days. You need to estimate 28 43 + 30 40 + 70 Answer: So, Samir rode his bike about 70 miles. Lesson 3 Ex2

2-3 Estimate Sums Devon wrote 27 sentences for homework on Monday and 14 sentences for homework on Wednesday. Estimate how many sentences he wrote on those two days. 40 sentences 41 sentences 30 sentences 50 sentences Lesson 3 CYP2

Answer: So, there were about 80 people on the circus floor.
2-3 Estimate Sums There were 65 clowns on the circus floor and 14 acrobats. About how many people were on the circus floor? You need to estimate 65 14 + 70 10 + 80 Answer: So, there were about 80 people on the circus floor. Lesson 3 Ex3

2-3 Estimate Sums There are 17 roller coasters and 32 other rides at Cedar Point Amusement Park. About how many rides are there altogether? 49 rides 50 rides 40 rides 45 rides Lesson 3 CYP3

End of Lesson 3

2-4 Two-Digit Addition Five-Minute Check (over Lesson 2-3) Main Idea and Vocabulary California Standards Example 1: Add with Regrouping Example 2: Partial Sums Example 3: Add without Regrouping Lesson 4 Menu

I will regroup ones and add two-digit numbers.
2-4 Two-Digit Addition I will regroup ones and add two-digit numbers. regroup Lesson 4 MI/Vocab

2-4 Two-Digit Addition Standard 3NS2.1 Find the sum or difference of two whole numbers between 0 and 10,000. Standard 3MR2.1 Use estimation to verify the reasonableness of calculated results. Lesson 4 Standard 1

You need to find the sum of 17 and 6.
2-4 Two-Digit Addition Jung found 17 seashells for his collection. His mother found six more. How many seashells do they have in all? You need to find the sum of 17 and 6. Estimate = 30 Step 1 Add the ones. 1 17 + 6 3 Lesson 4 Ex1

Answer: Jung and his mother found 23 seashells.
2-4 Two-Digit Addition Step 2 Add the tens. 17 6 + 3 1 2 Answer: Jung and his mother found 23 seashells. Check for Reasonableness Compare 23 to the estimate. The answer is reasonable. Lesson 4 Ex1

2-4 Two-Digit Addition Jolene collected 19 rubber bands. John collected 8. How many rubber bands do they have in all? 27 rubber bands 25 rubber bands 23 rubber bands 30 rubber bands Lesson 4 CYP1

You need to add 34 and 37. You can use partial sums.
2-4 Two-Digit Addition There are 34 girls and 37 boys in all the third grade classes. What is the total number of boys and girls in the third grade? You need to add 34 and 37. You can use partial sums. Estimate = 70 Lesson 4 Ex2

Answer: There are 71 boys and girls in the third grade.
2-4 Two-Digit Addition 34 + 37 60 Add the tens. + 11 Add the ones. 71 Add the partial sums. Answer: There are 71 boys and girls in the third grade. Check for Reasonableness Compare 71 to the estimate. The answer is reasonable. Lesson 4 Ex2

2-4 Two-Digit Addition In a survey of the third grade, 48 students had dogs and 24 had cats. What is the total number of dogs and cats owned by the third graders? 70 60 84 72 Lesson 4 CYP2

Find the sum of 74 + 24. Estimate 74 + 24 70 + 20 = 90 74 + 24 9 8
2-4 Two-Digit Addition Find the sum of Estimate = 90 4 ones + 4 ones = 8 ones 74 7 tens + 2 tens = 9 tens + 24 9 8 Answer: 98 Lesson 4 Ex3

Check for Reasonableness
2-4 Two-Digit Addition Check for Reasonableness Compare 98 to the estimate. The answer is reasonable. Lesson 4 Ex3

Find the sum of 45 + 33. 80 88 78 70 2-4 Two-Digit Addition
Lesson 4 CYP3

End of Lesson 4

2-5 Add Money Five-Minute Check (over Lesson 2-4) Main Idea and Vocabulary California Standards Example 1: Add Money Example 2: Add Money Lesson 5 Menu

I will learn to add money.
2-5 Add Money I will learn to add money. dollar sign ($) cents sign (¢) decimal point Lesson 5 MI/Vocab

2-5 Add Money Standard 3NS3.3 Solve problems involving addition, subtraction, multiplication, and division of money amounts in decimal notation and multiply and divide money amounts in decimal notation by using whole-number multipliers and divisors. Lesson 5 Standard 1

2-5 Add Money Standard 3MR2.1 Use estimation to verify the reasonableness of calculated results. Lesson 5 Standard 2

You need to find the sum of 61¢ + 15¢.
2-5 Add Money Alicia bought a pen for 61¢ and an eraser for 15¢. How much did she spend for the two items? You need to find the sum of 61¢ + 15¢. Estimate 61¢ + 15¢ ¢ + 20¢ = 80¢ Lesson 5 Ex1

Place the cents sign after the sum.
2-5 Add Money One Way: Add Cents 61¢ + 15¢ Add the ones. Add the tens. 7 6 Place the cents sign after the sum. Lesson 5 Ex1

Another Way: Add Dollars
2-5 Add Money Another Way: Add Dollars $0.61 + $0.15 $0.76 Answer: So, Alicia paid 76¢ or $0.76 for the two items. Lesson 5 Ex1

2-5 Add Money Check for Reasonableness 76¢ is close to the estimate of 80¢. So, the answer is reasonable. Lesson 5 Ex1

2-5 Add Money Seth bought a lollipop for 52¢ and a pack of gum for 36¢. How much money did he spend at the candy store? 90¢ $0.85 $0.88 80¢ Lesson 5 CYP1

2-5 Add Money Yin-Chin bought two DVDs. One cost $16, and the other was on sale for $6. How much did Yin-Chin spend for the two DVDs? You need to add $16 and $6. Estimate $16 + $ $20 + $10 = $30 Lesson 5 Ex2

Add the ones and regroup.
2-5 Add Money 1 $16 + $ 6 Add the ones and regroup. Add the tens. 2 $ 2 Place the dollar sign before the sum. Answer: So, Yin-Chin spent $22 on the two DVDs. Check for Reasonableness The answer $22 is close to the estimate of $30. So, the answer is reasonable. Lesson 5 Ex2

2-5 Add Money Sadako paid $27 for a CD at the store, and $14 for a CD online. How much did she spend on the two CDs? $41 $31 $50 $51 Lesson 5 CYP2

End of Lesson 5

2-6 Problem-Solving Investigation: Choose a Strategy Five-Minute Check (over Lesson 2-5) Main Idea California Standards Example 1: Problem-Solving Investigation Lesson 6 Menu

I will choose the best strategy to solve a problem.
2-6 Problem-Solving Investigation: Choose a Strategy I will choose the best strategy to solve a problem. Lesson 6 MI/Vocab

2-6 Problem-Solving Investigation: Choose a Strategy Standard 3MR1.1 Analyze problems by identifying relationships, distinguishing relevant from irrelevant information, sequencing and prioritizing information, and observing patterns. Lesson 6 Standard 1

2-6 Problem-Solving Investigation: Choose a Strategy Standard 3NS2.1 Find the sum or difference of two whole numbers between 0 and 10,000. Lesson 6 Standard 2

YOUR MISSION: Find out if they caught and kept at least 10 fish.
2-6 Problem-Solving Investigation: Choose a Strategy KIRI: My father and I needed to catch at least 10 fish. During the first hour, we caught 9 fish but threw 4 back. The second hour we caught 16 fish and threw 9 back. YOUR MISSION: Find out if they caught and kept at least 10 fish. Lesson 6 Ex1

Understand What facts do you know?
2-6 Problem-Solving Investigation: Choose a Strategy Understand What facts do you know? During the first hour, they caught 9 fish but threw 4 back. During the second hour, they caught 16 fish and threw 9 back. What do you need to find? Find out if they caught and kept at least 10 fish. Lesson 6 Ex1

2-6 Problem-Solving Investigation: Choose a Strategy Plan You need to find an exact answer. You can use addition and subtraction. Lesson 6 Ex1

Solve First, subtract to find out how many fish they kept.
2-6 Problem-Solving Investigation: Choose a Strategy Solve First, subtract to find out how many fish they kept. Hour One: – = Hour Two: – = Lesson 6 Ex1

Solve Next, add the total for each hour.
2-6 Problem-Solving Investigation: Choose a Strategy Solve Next, add the total for each hour. Answer: Kiri and her father caught and kept 12 fish. Lesson 6 Ex1

2-6 Problem-Solving Investigation: Choose a Strategy Check Look back at the problem. Yes, Kiri and her father caught and kept at least 10 fish. They caught 12. Lesson 6 Ex1

End of Lesson 6

Add Three-Digit Numbers
2-7 Three-Digit Addition Five-Minute Check (over Lesson 2-6) Main Idea California Standards Example 1: Add with Regrouping Example 2: Add with Regrouping Add Three-Digit Numbers Lesson 7 Menu

2-7 Three-Digit Addition I will add three-digit numbers and use estimation to check for reasonableness. Lesson 7 MI/Vocab

2-7 Three-Digit Addition Standard 3NS3.3 Solve problems involving addition, subtraction, multiplication, and division of money amounts in decimal notation and multiply and divide money amounts in decimal notation by using whole-number multipliers and divisors. Lesson 7 Standard

2-7 Three-Digit Addition Standard 3MR2.1 Use estimation to verify the reasonableness of calculated results. Lesson 7 Standard

2-7 Three-Digit Addition Lynda used 125 minutes of her cell phone minutes last week and 37 minutes this week. How many minutes has she used altogether? You need to add Estimate Lesson 7 Ex1

Step 2 Add the tens and hundreds.
2-7 Three-Digit Addition Step 1 Add the ones. 1 125 5 ones + 7 ones = 12 ones + 37 Regroup 12 ones as 1 ten and 2 ones. 2 Step 2 Add the tens and hundreds. 125 37 + 2 1 1 ten + 2 tens + 3 tens = 6 tens Bring the 1 hundred down. 1 6 Answer: Lynda has used 162 minutes altogether. Lesson 7 Ex1

2-7 Three-Digit Addition Check for Reasonableness Since 162 is close to the estimate of 170, the answer is reasonable. Lesson 7 Ex1

2-7 Three-Digit Addition Jesse used 143 minutes of his game trial period Monday and 47 minutes Tuesday. How many minutes has he used altogether? 200 minutes 189 minutes 190 minutes 100 minutes Lesson 7 CYP1

2-7 Three-Digit Addition Celli bought a book for $4.13 and a bookmark for $2.48. How much did she spend? Step 1 Add the ones. 1 $4.13 3 ones + 8 ones = 11 ones + $2.48 Regroup 11 ones as 1 ten and 1 one. 1 Lesson 7 Ex2

Step 2 Add the tens. $4.13 + $2.48 1 6 Step 3 Add the hundreds. $4.13
2-7 Three-Digit Addition Step 2 Add the tens. $4.13 + $2.48 1 1 ten + 1 ten + 4 tens = 6 tens 6 Step 3 Add the hundreds. $4.13 + $2.48 1 6 4 hundreds + 2 hundreds = 6 hundreds $6. Answer: Celli spent $6.61. Lesson 7 Ex2

2-7 Three-Digit Addition Julian spent $6.15 at the grocery store and $2.96 at the gas station. How much did he spend in all? $9.01 $9.11 $10.05 $8.99 Lesson 7 CYP2

End of Lesson 7

2-8 Add Greater Numbers Five-Minute Check (over Lesson 2-7) Main Idea California Standards Example 1: Real-World Example Example 2: Addition Methods Example 3: Addition of Money Lesson 8 Menu

Lesson 8 MI/Vocab/Standard 1
2-8 Add Greater Numbers I will add three- and four-digit numbers with regrouping. Lesson 8 MI/Vocab/Standard 1

2-8 Add Greater Numbers Standard 3NS3.3 Solve problems involving addition, subtraction, multiplication, and division of money amounts in decimal notation and multiply and divide money amounts in decimal notation by using whole-number multipliers and divisors. Lesson 8 Standard 1

2-8 Add Greater Numbers Standard 3MR2.1 Use estimation to verify the reasonableness of calculated results. Lesson 8 Standard 2

2-8 Add Greater Numbers In the library, there are 3,276 history books and 2,745 science books. What is the total number of these two types of books? You need to find 3, ,745. Estimate 3,276 + 2,745 3,300 + 2,800 6,100 Lesson 8 Ex1

One Way: Partial Sums 3,276 + 2,745 11 110 900 5,000 6,021 2-8
Add Greater Numbers One Way: Partial Sums 3,276 + 2,745 11 Add ones. 110 Add tens. 900 Add hundreds. 5,000 Add thousands. 6,021 Lesson 8 Ex1

Another Way: Expanded Notation
2-8 Add Greater Numbers Another Way: Expanded Notation 3,276 = 3, + 2,745 = 2, 5, 900 110 + 11 6,021 Answer: 6,021 books Lesson 8 Ex1

2-8 Add Greater Numbers At the video store there are 3,567 comedies and 2,655 dramas. What is the total number of these two types of videos? 7,225 6,222 8,032 5,111 Lesson 8 CYP1

2-8 Add Greater Numbers California’s tidal shoreline is 3,427 miles long. If you traveled from one end to the other and back, how many miles would you have traveled? Solve using at least two different methods. You need to find 3, ,427. Estimate 3,427 + 3,427 3,400 + 3,400 6,800 Lesson 8 Ex2

One Way: Partial Sums 3,427 + 3,427 14 40 800 6,000 6,854 2-8
Add Greater Numbers One Way: Partial Sums 3,427 + 3,427 14 Add ones. 40 Add tens. 800 Add hundreds. 6,000 Add thousands. 6,854 Lesson 8 Ex2

Another Way: Expanded Notation
2-8 Add Greater Numbers Another Way: Expanded Notation 3,427 = 3, + 3,427 = 3, 6, 800 40 + 14 6,854 Answer: 6,854 miles Lesson 8 Ex2

2-8 Add Greater Numbers It is 1,927 miles from Houston, Texas to San Francisco, California. If you traveled from one city to the other and back, how many miles would you have traveled? 3,004 miles 2,954 miles 6,004 miles 3,854 miles Lesson 8 CYP2

To add money, add as you would with whole numbers.
2-8 Add Greater Numbers Melody and her mother went to the botanical gardens. Her ticket cost $7.50 and her mother’s ticket cost $ Find the total cost. To add money, add as you would with whole numbers. Estimate $ $ $10 + $10 = $20 Lesson 8 Ex3

Answer: The total cost was $22.25.
2-8 Add Greater Numbers 1 1 Line up the decimal points. $14.75 + $ 7.50 Add. $ 2 2 . 2 5 Place the dollar sign in front of the dollars. Place the decimal point in the answer. Answer: The total cost was $22.25. Check for Reasonableness Since $22.25 is close to the estimate of $20, the answer is reasonable. Lesson 8 Ex3

2-8 Add Greater Numbers Theresa and her uncle went to the zoo. Her ticket cost $9.50 and her uncle’s cost $ Find the total cost. $29.50 $30.00 $30.75 $31.00 Lesson 8 CYP3

End of Lesson 8

2 Five-Minute Checks Math Tool Chest Image Bank
Addition 2 Five-Minute Checks Math Tool Chest Image Bank Add Three-Digit Numbers CR Menu

1. Exit this presentation.
To use the images that are on the following four slides in your own presentation: 1. Exit this presentation. 2. Open a chapter presentation using a full installation of Microsoft® PowerPoint® in editing mode and scroll to the Image Bank slides. 3. Select an image, copy it, and paste it into your presentation. IB Instructions

Lesson 2-1 (over Chapter 1) Lesson 2-2 (over Lesson 2-1)
Addition 2 Lesson 2-1 (over Chapter 1) Lesson 2-2 (over Lesson 2-1) Lesson 2-3 (over Lesson 2-2) Lesson 2-4 (over Lesson 2-3) Lesson 2-5 (over Lesson 2-4) Lesson 2-6 (over Lesson 2-5) Lesson 2-7 (over Lesson 2-6) Lesson 2-8 (over Lesson 2-7) 5Min Menu

Round 4,571 to the nearest thousand.
(over Chapter 1) Round 4,571 to the nearest thousand. 4,000 5,500 5,550 5,000 5Min 1-1

(over Chapter 1) Round 1,278 to the nearest thousand. 1,000 1,200 100 1,300 5Min 1-2

(over Chapter 1) Round 7,911 to the nearest thousand. 7,000 7,900 8,000 900 5Min 1-3

(over Chapter 1) Round 5,449 to the nearest thousand. 5,000 5,500 6,000 5,400 5Min 1-4

Find the sum. Tell which property you used.
(over Lesson 2-1) Find the sum. Tell which property you used. 9 + 5 = and = 4; Commutative Property 14; Commutative Property 14; Associative Property 4; Associative Property 5Min 2-1

(over Lesson 2-1) Find the sum. Tell which property you used. 6 + 0 = and = 6; Identity Property 6; Commutative Property 0; Commutative Property 0; Associative Property 5Min 2-2

(over Lesson 2-1) Find the sum. Tell which property you used. (3 + 6) + 4 = and 3 + (6 + 4) = 7; Associative Property 13; Identity Property 13; Associative Property 20; Associative Property 5Min 2-3

(over Lesson 2-2) Tell whether you need an estimate or an exact answer. Then solve. The school van holds 24 students. Mrs. Lazo has 9 girls and 17 boys in her class. Will the van hold all of the students in the class? estimate; no estimate; yes exact answer; no exact answer; yes 5Min 3-1

Estimate the sum using rounding.
(over Lesson 2-3) Estimate the sum using rounding. 70 90 80 60 5Min 4-1

Estimate the sum using rounding.
(over Lesson 2-3) Estimate the sum using rounding. 90 88 83 80 5Min 4-2

Estimate the sum using front-end estimation.
(over Lesson 2-3) Estimate the sum using front-end estimation. 50 47 40 30 5Min 4-3

Estimate the sum using front-end estimation.
(over Lesson 2-3) Estimate the sum using front-end estimation. 50 60 61 51 5Min 4-4

(over Lesson 2-4) Find the sum. 37 + 4 41 40 33 34 5Min 5-1

(over Lesson 2-4) Find the sum. 90 70 95 100 5Min 5-2

(over Lesson 2-5) Find the sum. 35¢ + 4¢ 39¢ 32¢ 75¢ 31¢ 5Min 6-1

(over Lesson 2-5) Find the sum. $18 + $28 $36 $46 $48 $10 5Min 6-2

Find the sum. $0.23 + $0.08 $0.34 $0.13 $0.31 $0.41 (over Lesson 2-5)
5Min 6-5

yes; 20 + 30 = 50, which is more than 40
(over Lesson 2-6) Use one of the problem-solving strategies to solve. The farmer bought 19 cows in May and 26 in June. Did he buy more than 40 cows in all? no; = 40 yes; = 40 no; 30 – 20 = 10 yes; = 50, which is more than 40 5Min 7-1

Find the sum. Use estimation to check for reasonableness.
(over Lesson 2-7) Find the sum. Use estimation to check for reasonableness. 571 575 669 569 5Min 8-1

(over Lesson 2-7) Find the sum. Use estimation to check for reasonableness. $ $1.09 $8.88 $6.80 $8.98 $7.08 5Min 8-3

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