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Splash Screen. Five-Minute Check (over Lesson 3–2) Main Idea Example 1: Real-World Example Example 2: Real-World Example Example 3: Compatible Numbers. Lesson Menu. I will estimate products by using rounding and compatible numbers. Main Idea/Vocabulary. 67. × 32.
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Five-Minute Check (over Lesson 3–2) Main Idea Example 1: Real-World Example Example 2: Real-World Example Example 3: Compatible Numbers Lesson Menu
I will estimate products by using rounding and compatible numbers. Main Idea/Vocabulary
67 × 32 Estimate 67 × 32. Round each number to the nearest ten. One Way: Round one factor. THINK It is easier to compute 67 × 30 than 67 × 32. 67 × 30 Round 32 to the nearest ten. 2,010 Find 67 × 30 mentally. Example 1
67 × 32 Estimate 67 × 32. Round each number to the nearest ten. Another Way: Round both factors. 70 Round 67 to the nearest ten. × 30 Round 32 to the nearest ten. 2,100 Find 70 × 30 mentally. Example 1
Answer: So, depending on how you estimate, 67 × 32 is about 2,010 or 2,100. Example 1
A B C D Estimate 58 × 42. • 2,000 • 2,400 • 2,500 • 3,000 Example 1
Round each factor to its greatest place value. One Way: 189 × 24 The students at DeSales Middle School collected cans for recycling. In one week, each of the 24 classes collected 189 cans. About how many cans did they collect that week? 200 Round 189 to the nearest hundred. × 20 Round 24 to the nearest ten. 4,000 Find 200 × 20 mentally. Example 2
189 × 24 Another Way: Round 189 to the nearest hundred. 200 Round 189 to the nearest hundred. × 24 4,800 Find 200 × 24 mentally. Example 2
189 × 24 Another Way: Use compatible numbers. 200 200 and 25 are compatible numbers. × 25 5,000 Find 200 × 25 mentally. Example 2
Answer: Depending on how you round, 189 × 24 is about 4,000, 4,800, or 5,000. So, the students collected between 4,000 and 5,000 cans. Example 2
A B C D A school collected soup labels for a fund raiser. In two weeks, each of the 33 classes collected 296 can labels. About how many labels did the school collect in all? • 9,000 labels • 9,500 labels • 10,000 labels • 11,000 labels Example 2
Compatible Numbers Jared earns $24 per week mowing lawns. About how much does he earn per month? 24 × 4 → 25 × 4 Replace 24 with 25. 24 × 4 = 100 THINK Four quarters are the same as $1.00. So, 25 × 4 = 100. Answer: Jared earns about $100 per month. Example 3
A B C D A car wash is used by 54 cars per day. About how many cars use the car wash in one month? • 900 cars • 1,200 cars • 1,400 cars • 1,500 cars Example 3
End of the Lesson End Lesson
Five-Minute Check (over Lesson 3–2) Image Bank Math Tool Chest Multiply Mentally Resources
A B C D (over Lesson 3–2) Find 48 × 3 mentally using the Distributive Property. Show the steps that you used. • 3 × (40 + 8) = (3 × 40) + (3 × 8) = 120 + 24 = 144 • (3 × 40) × (3 × 8) = 120 × 24 = 2,880 • (3 × 40) + 8 = 120 + 8 = 128 • (3 × 40) + (48 × 3) = 264 Five Minute Check 1
A B C D (over Lesson 3–2) Find 5 × 64 mentally using the Distributive Property. Show the steps that you used. • (5 × 60) × (5 × 4) = 300 × 20 = 6,000 • (5 × 60) + 4 = 300 + 4 = 304 • 5 × (60 + 4) = (5 × 60) + (5 × 4) = 300 + 20 = 320 • (5 × 60) + (64 × 5) = 1,820 Five Minute Check 2
A B C D (over Lesson 3–2) Find 87 × 4 mentally using the Distributive Property. Show the steps that you used. • (4 × 80) × (4 × 7) = 320 × 28 = 8,960 • 4 × (80 + 7) = (4 × 80) + (4 × 7) = 320 + 28 = 348 • (4 × 80) + 7 = 320 + 7 = 327 • (4 × 87) + (4 × 80) = 668 Five Minute Check 3
A B C D (over Lesson 3–2) Find 6 × 54 mentally using the Distributive Property. Show the steps that you used. • 6 × (50 + 4) = (6 × 50) + (6 × 4) = 300 + 24 = 324 • (6 × 50 × 4) = (6 × 50) × (6 × 4) = 300 × 24 = 7,200 • (6 × 50) + 4 = 300 + 4 = 304 • (6 × 54) + (6 × 50) = 324 + 300 = 624 Five Minute Check 4