Lesson 6 Use a Ten to Add Within 1,000

- Let’s add three-digit numbers by composing a ten.

Warm-up Number Talk: Numbers that Make 10

Find the value of each expression mentally.

$28 + 2$
$28 + 12$
$67 + 3$
$67 + 23$

Activity 1 Add Two-digit and Three-digit Numbers

Find the value of each sum.
Set 1
Set 2
Set 3
$245 + 15 =$
$134 + 26 =$
$351 + 19 =$
$247 + 23 =$
$133 + 37 =$
$356 + 24 =$
$249 + 31 =$
$138 + 42 =$
$355 + 35 =$
What patterns did you notice?

Activity 2 Card Sort: Perfect Ten

Match each three-digit number to a two-digit number. When you add your numbers together they should make a ten with no extra ones.
Pick 1 pair of numbers and find the value of their sum. Show your thinking.

Practice Problem

Problem 1

Find the value of each sum. Show your thinking.

$238 + 52$
$252 + 38$
$119 + 61$