Main content

## 1st grade

### Course: 1st grade > Unit 2

Lesson 2: Addition within 20# Add 3 numbers

## Problem

Stuck?

Stuck?

If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains ***.kastatic.org** and ***.kasandbox.org** are unblocked.

Main content

Stuck?

Stuck?