# Lesson 15 Estimate and Subtract

• Let’s use place value to subtract decimals.

## Warm-up Number Talk: One and Five Tenths

Find the value of each expression mentally.

## Activity 1 Revisit the Algorithm

1. Find the value of . Show your reasoning.

2. Han used the standard algorithm to subtract decimals. This is Han’s work. Describe what Han did in each step.

3. Use the standard algorithm to find the value of .

## Activity 2 Estimate and Subtract

1. Which whole number is the difference closest to? Explain or show your reasoning.

2. What is the value of ? Explain or show your reasoning.

3. Which whole number is the difference  closest to? Explain or show your reasoning.

4. What is the value of ? Explain or show your reasoning.

## Activity 3 Compare Calculations to Evaluate a Difference

1. Find the value of . Explain or show your reasoning.

2. Elena and Andre found the value of . Who do you agree with? Explain or show your reasoning.

## Problem 1

1. Here is how Elena found the value of .

Explain Elena’s calculations and the meaning of the 15 above the 5 and the 17 above the 7 in 15.37.

2. Use Elena’s algorithm to calculate .