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Lesson Menu Five-Minute Check (over Lesson 2–1) Main Idea and Vocabulary Example 1:Use Rounding with Whole Numbers Example 2:Use Compatible Numbers Example 3:Use Rounding with Decimals
Main Idea/Vocabulary I will estimate sums and differences by rounding and using compatible numbers. estimate compatible numbers
Example 1 Use Rounding with Whole Numbers Estimate 923 – 415 by rounding. Round each number to the nearest hundred. Then subtract. – – Answer: So, 923 – 415 is about is closer to 900 than 1, is closer to 400 than 500.
1.A 2.B 3.C 4.D Example 1 A.400 B.500 C.550 D.600 Estimate 812 – 376 by rounding.
Example 2 Use Compatible Numbers Gareth’s cat weighs 9.3 pounds. Dieter’s dog weighs 28.9 pounds. Use compatible numbers to estimate the difference. Find two numbers that you can easily subtract. – – Answer: So, the difference is about 20 pounds is close to is close to 10.
1.A 2.B 3.C 4.D Example 2 A.90 B.80 C.50 D.40 Use compatible numbers to estimate the difference 89.3 – 52.2.
Example 3 Use Rounding with Decimals Karim wants to buy a baseball mitt that costs $13.95 and a baseball that costs $8.47. Estimate the cost of the two items. One Way Round to the nearest ten. $ $ + + $ $ $ Another Way Round to the nearest whole number. $ $ + + $ $ 8.00 $
Example 3 Use Rounding with Decimals Answer: Depending on how the numbers are rounded, the difference in cost is about $20.00 or $ The actual cost is $ So, rounding to the nearest whole number gave the more accurate estimate.
1.A 2.B 3.C 4.D Example 3 A.$2.00 B.$4.00 C.$8.00 D.$20.00 Estimate the difference in the cost of $12.49 and $7.54.
End of the Lesson End Lesson
Resources Five-Minute Check (over Lesson 2–1) Image Bank Math Tool Chest Add and Subtract Decimals
1.A 2.B 3.C 4.D Five Minute Check 1 (over Lesson 2–1) A.12,340 B.12,350 C.12,300 D.12,400 Round 12,345 to the underlined place.
1.A 2.B 3.C 4.D Five Minute Check 2 (over Lesson 2–1) A B C D Round to the underlined place.
1.A 2.B 3.C 4.D Five Minute Check 3 (over Lesson 2–1) A.82.1 B.83.0 C.82 D Round to the underlined place.
1.A 2.B 3.C 4.D Five Minute Check 4 (over Lesson 2–1) A.9.2 B.10 C.9.17 D.9 Round to the underlined place.
1.A 2.B 3.C 4.D Five Minute Check 5 (over Lesson 2–1) A B C D Round to the tenths place.
1.A 2.B 3.C 4.D Five Minute Check 6 (over Lesson 2–1) A B.580 C D Round to the tens place.
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