2.5. Estimate with 2-Digit Divisors. Unlock the Problem. Essential Question. Name. Module 2 79

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1 ? Name 2.5 Essential Question Estimate with 2-Digit Divisors How can you use compatible numbers to estimate quotients? Number and Operations 5.3.A MATHEMATICAL PROCESSES 5.1.F, 5.1.G Connect You can estimate quotients using compatible numbers that are found by using basic facts and patterns = 7 basic fact = 7 3, = 70 35, = 700 Unlock the Problem The observation deck of the Willis Tower in Chicago, Illinois, is 1,353 feet above the ground. Elevators lift visitors to that level in 60 seconds. About how many feet do the elevators travel per second? STEP 1 Estimate. 1, Use two sets of compatible numbers to find two different estimates. 1, , , , Willis Tower, formerly known as the Sears Tower, is the tallest building in the United States. STEP 2 Use patterns and basic facts to help estimate = _ = _ 1, = _ 18 6 = _ = _ = _ The elevators travel about _ to _ feet per second. The more reasonable estimate is because is closer to 1,353 than is. So, the observation deck elevators in the Willis Tower travel about _ feet per second. Module 2 79

2 Example Estimate money. Miriam has saved $650 to spend during her 18-day trip to Chicago. She doesn t want to run out of money before the trip is over, so she plans to spend about the same amount each day. Estimate how much she can spend each day. Estimate. 18 ) $650 Math Talk Mathematical Processes Would it be more reasonable to have an estimate or an exact answer for this example? Explain your reasoning. $600 _ = $30 or 20 = $40 So, Miriam can spend about to each day. Given Miriam s situation, which estimate do you think is the better one for her to use? Explain your reasoning. Try This! Use compatible numbers. Find two estimates. 52 ) 415 Estimate the quotient. 38 ) $2,764 Share and Show Use compatible numbers to find two estimates ) ) ) 7, = _ = _ ) ) 2, ) 5,312 80

3 Name Problem Solving Use compatible numbers to estimate the quotient ) ) $ ) 7,130 Practice: Copy and Solve Use compatible numbers to estimate the quotient , , Write Math Explain how you know whether the quotient of is closer to 9 or to 10. Problem Solving Use the picture to solve About how many meters tall is each floor of the Chrysler Building? 16. Multi-Step Use estimation to decide which building has the tallest floors. About how many meters is each floor? 275 meters, 64 floors, Williams Tower, Texas 295 meters, 76 floors, Columbia Center, Washington 319 meters, 77 floors, Chrysler Building, New York 17. Eli needs to save $235. He plans to mow lawns and charge $21 for each. Write two estimates for the number of lawns he needs to mow. Decide which estimate you think is the better one for Eli to use. Explain your reasoning. Module 2 Lesson 5 81

4 Daily Assessment Task Mathematical Processes Fill in the bubble completely to show your answer. 18. A meteoroid travels 18 miles per second and is 2,863 miles away from the moon. Estimate how long it will take the meteoroid to reach the moon. A 120 seconds C 200 seconds B 150 seconds D 280 seconds 19. Apply A playground is 5,583 feet away from Jake s house. Jake runs 17 feet per second. Which is the best estimate of the amount of time it will take Jake to run to the park? A B C D 5, = 260 seconds 6, = 300 seconds 6, = 600 seconds 5, = 500 seconds 20. Multi-Step At an orchard, 486 green apples are to be organized into 12 green baskets, and 633 red apples are to be organized into 31 red baskets. Use estimation to decide which color basket has more apples. About how many apples are in each basket of that color? A B C D red basket, 50 apples green basket: 20 apples red basket, 20 apples green basket: 50 apples TEXAS Test Prep 21. Anik built a tower of cubes. It was 594 millimeters tall. The height of each cube was 17 millimeters. About how many cubes did Anik use? 82 A 10 B 300 C 30 D 16

5 Homework and Practice Name Number and Operations 5.3.A MATHEMATICAL PROCESSES 5.1.F, 5.1.G 2.5 Estimate with 2-Digit Divisors Use compatible numbers to find two estimates ) ) ) 6,078 Use compatible numbers to estimate the quotient. 4. 7, , , , , , Problem Solving 12. Alec needs to save $376. He plans to rake fall leaves for $12 per lawn. Using compatible numbers, write an estimate that shows the number of lawns he will need to rake. 13. Mr. Rodriguez s construction company built an office building that is 1,848 feet tall. Each floor of the building is 14 feet high. About how many floors are in the building? Write an estimate. Module 2 Lesson 5 83

6 Lesson Check TEXAS Test Prep Fill in the bubble completely to show your answer. 14. Which number sentence with compatible numbers is the most reasonable estimate of the quotient for ? A = 20 B = 10 C = 8 D = Leo has 279 comic books in his collection. He puts 34 comic books in each box. About how many boxes of comic books does Leo have? A 6 B 11 C 9 D Cameron wants to buy a bike for $268. He saves $53 each month from his job. Which is the best estimate of the number of months it will take him to save enough to buy the bike? A B C D = 3 months = 5 months = 6 months = 4 months 17. The Alam family has saved $260 to spend on entertainment activities for one week. They want to spend about the same amount of money each day. Which is the best estimate of how much they can spend each day? A $280 7 = $40 B $ = $26 C $240 6 = $40 D $270 9 = $ Multi-Step At the recycling center, 394 cans are to be organized into 10 green bins, and 560 bottles are to be organized into 12 blue bins. Use estimation to decide which type of bin has more items. About how many items are in this bin? A blue bin, 60 B blue bin, 40 C green bin, Multi-Step Farmer Theo sells cases of chicken eggs with 30 dozen eggs in a case. If he has 9,370 eggs, about how many cases of eggs does he have? A 20 B 17 C 30 D 35 D green bin, 40 84