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Making Change

Part of the Decimals, Percents & Ratios section of Coddy's Pre-Algebra journey. Lesson 6 of 53.

You buy a 6.45 dollar book and a 3.80 dollar snack. You pay with a 20 dollar note. The cashier gives you 10.75 dollars back. Should you say something?

Yes: that is one dollar too much. Change is the note minus the prices. $20-6.45-3.8$ is $13.55-3.8$ , which is 9.75.

You can also add the prices first: 6.45 plus 3.80 is 10.25. Then $20-10.25$ is 9.75.

Challenge

Mia buys a 17.85 dollar T-shirt and a 12.40 dollar cap. She pays with a 50 dollar note. Find her change c. Write c equal to the calculation, then work it out.

Start the lesson to read it in the interactive player and track your progress.

All lessons in Decimals, Percents & Ratios

1Decimals

Place Value Rounding Decimals Recap: Decimals

4Dividing Decimals

Dividing by a Decimal Dividing by 10 and 100 Dividing by a Whole Number Unit Price Recap: Dividing

7Percent Problems

Finding the Whole Discounts Tax and Tips Percent Increase Percent Decrease Recap: Percent Problems

10Proportions

Solving a Proportion Cross Products Scale Drawings Percent as a Proportion Recap: Proportions

2Adding and Subtracting

Line Up the Points Negative DecimalsMaking ChangeRecap: Add and Subtract

5Fractions and Decimals

Fraction to Decimal Decimal to Fraction Repeating Decimals Ordering Both Kinds Recap: Fractions and Decimals

8Ratios

What a Ratio Is Simplifying Ratios Equivalent Ratios Sharing in a Ratio Recap: Ratios

11Final Challenges

Final: Decimals and Percents Final: The Jacket Final: Out of a Hundred Final: The Apple Stall Final: On the Line

3Multiplying Decimals

Multiplying Decimals Times 10, 100, 1000 Bigger Products Buying by Weight Recap: Multiplying

6Percent Basics

What Percent Means Percent of a Number Percent as a Decimal What Percent Is It Recap: Percent Basics

9Rates

Unit Rates The Better Buy Speed, Distance, Time Converting Units Recap: Rates