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.

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.

Practice Problem

Problem 1

  1. Find the value of each difference.

  2. Jada drew this picture to find the value of a difference. What difference did Jada calculate? Explain how you know.

    Base ten diagram. 2 hundreds, 1 crossed out. 5 tens, 2 crossed out, one with arrow pointing to 10 ones, 1 crossed out. 7 ones, all crossed out.