Lesson 12 Decompose to Subtract

- Let’s subtract within 1,000.

Warm-up What Do You Know About …?

What do you know about 354?

How could we represent the number 354?

Activity 1 Subtract from 354

Find the value of each expression in any way that makes sense to you. Explain or show your reasoning.

$354 - 7$
$354 - 36$
$354 - 48$

Activity 2 Decompose With Base-ten Blocks

Students with base ten blocks.

Work with your partner to find the value of each expression.

Partner A: Read the expression and represent the larger number using blocks.
Partner B: Decide if you will decompose a ten and explain. Then subtract.
Discuss and write the difference.
Switch roles.

$264 - 38$
$274 - 41$
$336 - 115$
$343 - 127$
$485 - 266$
$451 - 315$

Practice Problem

Problem 1

Find the value of each difference.
- $325 - 19$
- $437 - 115$
Jada drew this picture to find the value of a difference. What difference did Jada calculate? Explain how you know.