Unit 4, Lesson 8-- Using Rounding to Help Find Reasonable Answers for Addition and Subtraction

Lesson 8-- Using Rounding to Help Find Reasonable Answers for Addition and Subtraction

Introduction

Hello Mathematicians! Today we will work on finding reasonable answers for addition and subtraction problems by rounding to the nearest ten before solving.

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Video

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Assignment

Directions:

• Determine what would be a reasonable answer to the following problems by using rounding to the nearest ten before solving.
• In your notebook, explain what you think would be a reasonable answer and how you came to this conclusion.

  • $429 + $353 = $?

  • $589 - $243 = $?

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In Your Math Notebook:

Let’s get out our math journals and  work through the following application problem. Make sure you read the problem carefully, draw a picture to match your thinking and write and solve an equation.

Remember sometimes we don’t need an exact answer. Look for key works like “about” to help you know when an estimate is expected to be given. Make sure you use your knowledge of rounding to the nearest ten!

Read, Draw, Write. DONE!

R (Read the problem carefully.) The grocery store had 138 bananas and 392 apples. About how many pieces of both types of fruit did they have total? D (Draw a picture.) W (Write and solve an equation.)

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