# Lesson 4 Add and Subtract Three-digit Numbers in Different Ways

• Let’s add and subtract three-digit numbers.

## Warm-up Number Talk: Count Back by Place

Find the value of each expression mentally.

## Activity 1 Zero Tens and Zero Ones

Mai and Lin were asked to find the value of .
Here is their work.

Mai’s Work:

Lin’s Work:

Find the value of each expression.

1. Try Mai’s way to find .

2. Try Lin’s way to find  .

## Activity 2 Add or Subtract with Expanded Form

1. Andre and Diego showed their thinking with equations to find the value of .

Andre’s Work

Diego’s Work

What is the same or different about their work?

2. Try Andre’s way to find the value of .

3. Try Diego’s way to find the value of .

4. Choose your own way to find the value of . Show your thinking.

5. Choose your own way to find the value of . Show your thinking.

## Problem 1

1. Find the value of . Show your thinking.

2. Find the value of . Show your thinking.