Main content

## Class 1

### Course: Class 1 > Unit 2

Lesson 6: Missing numbers within 20# Find missing number (add and subtract within 20)

## 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?