5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini Lesson 17: I can use basic facts to estimate quotients with two-digit divisors. 5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini

Get Your White Board Ready & Let’s Practice Rounding Round Each Number to the Nearest Ten 54 = ___ 16 = ___ 73 = ___ 65 = ___ 37 = ___ 21 = ___ 25 = ___ 50 20 70 40 30 70 20 5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini

Get Your White Board Ready! 700 ÷ 10 = 70 700 ÷ 10 Say this division sentence with the quotient. Write this equation as a two-step sentence taking out the ten. 800 ÷ 20 800 ÷ 10 ÷ 2 Below the two-step division sentence, rewrite it in one-step after solving the first part. 80 ÷ 2 Write the quotient. 40 5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini

Get Your White Board Ready! Write this equation as a two-step sentence taking out the ten. 15,000 ÷ 30 15,000 ÷ 10 ÷ 3 Below the two-step division sentence, rewrite it in one-step after solving the first part. 1,500 ÷ 3 Write the quotient. 500 5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini

Get Your White Board Ready! Write this equation as a two-step sentence taking out the ten. 15,000 ÷ 300 15,000 ÷ 100 ÷ 3 Below the two-step division sentence, rewrite it in one-step after solving the first part. 150 ÷ 3 Write the quotient. 50 5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini

Get Your White Board Ready! Write this equation as a two-step sentence taking out the ten. 450,000 ÷ 50 450,000 ÷ 10 ÷ 5 Below the two-step division sentence, rewrite it in one-step after solving the first part. 45,000 ÷ 5 Write the quotient. 9,000 5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini

Get Your White Board Ready! Write this equation as a two-step sentence taking out the ten. 21,000 ÷ 300 21,000 ÷ 100 ÷ 3 Below the two-step division sentence, rewrite it in one-step after solving the first part. 210 ÷ 3 Write the quotient. 70 5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini

5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini Application Problem 852 pounds of grapes were packed equally into 3 boxes for shipping. How many pounds of grapes will there be in 2 boxes? Solution on next slide… 5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini

5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini Solution 5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini

Concept Development 402 ÷ 19 402 What’s the whole (or dividend) in this problem? Let’s use rounding to find an estimated quotient! We can round 402 to 400 since I can use mental math to divide 400 by 20. Now let’s solve. Remember to take out the 10 to help you. First, let’s round the divisor to the nearest ten! 19 ≈ 20 Let’s record our estimation below. We need to round our whole, 402, to a number that can easily be divided by 20. Turn and share your ideas to your partner. 19 What’s the divisor? 402 ÷ 19 ≈ ____ ÷ 20 400 ÷ 10 ÷ 2 40 ÷ 2 20 5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini

149 ÷ 71 ≈ 2 149 ÷ 71 149 ÷ 71 ≈ ____ ÷ 70 Take out our journal. Problem 2 149 ÷ 71 ≈ 2 149 ÷ 71 Take out our journal. Let’s estimate the quotient. What do we do first? Let’s solve. Taking out the 10 in 70. 1st – Round the Divisor 71 ≈ 70 149 ÷ 71 ≈ ____ ÷ 70 140 2nd – Round the Whole (dividend) ÷ 10 ÷ 7 14 ÷ 7 Think… When we round for division we want to make sure our dividend is a multiple of the divisor. We have to think of the nearest multiple of 70. Let’s list our multiples of 70. = 2 Multiples of 70: 70 140 210 280 149 is closest to which multiple of 70? 5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini

427 ÷ 58 Work with your partner and solve the estimated quotient. Problem 3 427 ÷ 58 Work with your partner and solve the estimated quotient. Remember we are finding the estimated quotient! Volunteer to Share Solution: Round the Divisor List the multiples of the rounded divisor to find the one that is closest to 427 Use the closest multiple as your rounded whole number. Divide using the rounded digits. Check to see if your estimated quotient makes sense. Solution on next slide… 5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini

5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini Solution 427 ÷ 58 ≈ 420 ÷ 60 420 ÷ 10 ÷ 6 42 ÷ 6 ≈ 7 427 ÷ 58 ≈ 7 5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini

Problem 4 293 ÷ 42 Let’s find the estimated quotient for this problem! Record in your math journal. Round the divisor. 42 ≈ 40 280 is closer. Let’s divide now! Try it on your own in your journal. ÷ 40 280 ÷ 10 ÷ 4 28 ÷ 4 7 293 ÷ 42 ≈ 7 Round the whole number to a multiple of 40 by listing the multiples of 40 40 80 120 160 200 240 280 320 Wait! Our whole is between 280 & 320. Which multiple is closer to 293? Visualize it on a number line. 5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini

751 ÷ 93 Work independently to estimate the quotient. Check your work with your partner. Solution (use ink tools): 5th Grade Module 2 – Lesson 17 Created by Leigh-Ann Pieragostini

Get Ready to Complete the Problem Set on Your Own! Complete Pages 2.E.22 & 2.E.23 You will have 15 minutes to work. Try your Best! 5th Grade Module 2 – Lesson 16

5th Grade Module 2 – Lesson 16 LET’S Debrief Look back at the divisors in Problem 1 (l), (m), and (n). What did you notice about them? How did the 5 in the ones place affect the way you rounded? In Problem 1(o), did anyone leave the divisor 11, unrounded? Is it always necessary to round? Do we follow our typical rounding rules when estimating with division? Why not? 5th Grade Module 2 – Lesson 16

5th Grade Module 2 – Lesson 16 EXIT TICKET Page 2.E.24 5th Grade Module 2 – Lesson 16