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Lesson 19: I can divide two and three digit dividends by multiples of 10 with single digit quotients
and make connections to a written method.
5th Grade Module 2 – Lesson 19
Estimate and Divide
5th Grade Module 2 – Lesson 19
908 ÷ 28 Say the divisor rounded to the nearest ten…÷ 30
Name the multiple of 30 that’s closest
to 900…900
Estimate the value…
30
Estimate and Divide
5th Grade Module 2 – Lesson 19
152 ÷ 33 Say the divisor rounded to the nearest ten…÷ 30
Name the multiple of 30 that’s closest
to 152…150
Estimate the value…
5
Estimate and Divide
5th Grade Module 2 – Lesson 19
398 ÷ 98 Say the divisor rounded to the nearest ten…÷ 10
0
Name the multiple of 100 that’s closest to
398…400
Estimate the value…
4
Estimate and Divide
5th Grade Module 2 – Lesson 19
7,272 ÷ 81 Say the divisor rounded to the nearest ten…÷ 80
Name the multiple of 80 that’s closest
to 7,272…7,200
Estimate the value…
90
Application Problem
5th Grade Module 2 – Lesson 19
At the Highland Falls pumpkin growing contest, the prize winning pumpkin
contains 360 seeds. The proud farmer plans to sell his seeds in packs of 12. How many packs can he
make using all the seeds?Solution on next slide…
5th Grade Module 2 – Lesson 18
Solution
360 ÷ 12 =(36 ÷ 12) x 10 =
3 x 10 =30 packets
Think of 360 as 36
tens…
5th Grade Module 2 – Lesson 18
Concept Development
70 ÷ 30
What’s the whole (or dividend) in this problem?
70
What’s the divisor? 30
Let’s use rounding to find an estimated quotient!
70 ÷ 30 ≈ ÷ 3060
2
Check:30 x 2 = 60
We are 10 off from 70!
10 is the remainder!
PreciseAnswer:2 R10
5th Grade Module 2 – Lesson 19
Concept Development
430 ÷ 60
What’s the whole (or dividend) in this problem?
430
What’s the divisor? 60
Let’s use rounding to find an estimated quotient!
430 ÷ 60 ≈ ÷ 60
≈ 7 420
7 groups of 60
Check:60 x 7 = 420
We are 10 off from 430!
10 is the remainder!
PreciseAnswer:7 R10
5th Grade Module 2 – Lesson 19
Let’s Try That One Again Using the Standard Algorithm!
430 ÷ 60 = 7 60 430
Why is the 7 placed above
the zero?-420 10
R 10
Check: 60 x 7 = 420
(add the remainder!) 420 + 10 = 430
5th Grade Module 2 – Lesson 18
Work independently to estimate the quotient. Check your work with your partner.
Solution (use ink tools):
572 ÷ 90
5th Grade Module 2 – Lesson 18
Get Ready to Complete theProblem Set on Your Own!
Complete Pages 2.F.8 & 2.F.9You will have 15 minutes to work.
Try your Best!
5th Grade Module 2 – Lesson 18
LET’S DEBRIEF• Did anyone notice something different? Does it always make
sense to use the standard algorithm?
• In problem 2, what was Terry’s mistake? If you had to estimate the quotient, what would you have done? What could he do to correct his mistake without erasing his work so far?
• What if Terry had estimated too large a quotient? What should he do?
• How was solving Problem 3 different from solving all the others?
• What did all our divisors have in common today? Did this make estimation easier?
5th Grade Module 2 – Lesson 18
EXITTICKETPage 2.F.10
