# Section A: Practice Problems Add and Subtract Within 1,000 Without Composition or Decomposition

## Section Summary

## Details

In this section of the unit, we compared three-digit numbers and looked at how addition can be used to find the difference, especially when numbers are close together. We added and subtracted by counting on or back by place and used expanded form to think about adding or subtracting using place value based strategies.

## Problem 1 (Pre-Unit)

Select **all** representations of the number 318.

Three hundred eighteen

Three hundred eighty-one

## Problem 2 (Pre-Unit)

Write a number for each representation.

Five hundred twenty-seven

## Problem 3 (Pre-Unit)

Find the value of each sum or difference. Show your thinking.

## Problem 4 (Pre-Unit)

Find the value of each difference.

## Problem 5 (Lesson 1)

Find the value of each difference. Show your thinking.

## Problem 6 (Lesson 2)

Here are Kiran’s blocks.

He gives 2 tens to Priya.

What is the value of Kiran’s blocks now? Show your thinking.

Then Priya gives Kiran 4 hundreds.

What is the value of Kiran’s blocks now? Show your thinking.

## Problem 7 (Lesson 3)

Find the value of each difference. Show your thinking. Use a number line or base-ten blocks if it helps.

## Problem 8 (Lesson 4)

Find the value of

. Show your thinking. Find the value of

. Show your thinking.

## Problem 9 (Lesson 5)

Find the value of each expression. Explain your reasoning.

## Problem 10 (Exploration)

Here is Han’s work finding the value of a difference.

What difference did Han find? Show your reasoning.

Write an addition and a subtraction equation that match Han’s work.

## Problem 11 (Exploration)

Tyler says he can find the value of

“First I find

Use Tyler’s reasoning to find the value of