Grade 3 Unit 3
Lesson 11: Analyze Subtraction Algorithms
CC BY 2021 Illustrative Mathematics®
Grade 3 Unit 3
Lesson 11: Analyze Subtraction Algorithms
CC BY 2021 Illustrative Mathematics®
Find the value of each expression mentally.
400 - 200
450 - 200
450 - 205
450 - 215
The first steps of two algorithms are shown.
How are the steps different?
Use Algorithm A to find the value of 824 - 541.
Use Algorithm B to find the value of 824 - 541.
Noah wanted to find the value of 301 - 167 and wrote:
Elena said that we can’t subtract this way because we would need more ones to subtract 7 ones, but there’s a zero in the tens place of 301.
Do you agree with Elena's statement? Explain your reasoning.
Show how you would use an algorithm (either Noah's or another algorithm) to find the difference between 301 and 167.
What is your favorite way to subtract large numbers?
What’s a way that you would like to learn more about and use more?
