# Lesson 15 Decompose a Ten and a Hundred to Subtract

• Let’s subtract within 1,000.

## Warm-up Choral Count: Hundreds and Tens

Count back by 10, starting at 590.

What patterns do you see?

## Activity 1 Elena’s Thinking

Elena’s thinking:

Step 1:

Step 2:

Step 3:

1. Use base-ten blocks or a base-ten diagram to show Elena’s steps.

2. Finish Elena’s work to find the value of .

3. What is another way you could use numbers or equations to show subtracting by place to find the value of ?

## Activity 2 Walk About and Subtract

• Find someone with a different number than you.

• Find the difference between your numbers.

• Trade cards and find a new partner.

1. Partner 1:

2. Partner 2:

3. Partner 3:

## Problem 1

Find the value of each difference. Show your thinking.