# Lesson 9 Add Three-digit Numbers

• Let’s practice adding within 1,000.

## Warm-up Number Talk: Ten and Some More

Find the value of each expression mentally.

## Activity 1 How Did You Add Three-digit Numbers?

Find the value of each expression. Show your thinking.

## Activity 2 Analyze and Add

Noah and Kiran showed how they found the value of .

Noah’s work

Kiran’s work

1. How is Noah and Kiran’s work the same? How is it different?

2. Which student found the correct value? Explain or show your thinking.

## Problem 1

Here is how Jada found the value of .