Pre-Algebra Essentials For Dummies

Chapter 6

Puzzling Out Percents

IN THIS CHAPTER

Understanding what percents are

Converting percents back and forth between decimals and fractions

Solving both simple and difficult percent problems

Using the percent circle to solve three types of percent problems

Like whole numbers and decimals, percents are a way to talk about parts of a whole. The word percent literally means “for 100,” but in practice, it means closer to “out of 100.” For example, suppose a school has exactly 100 children — 50 girls and 50 boys. You can say that “50 out of 100” children are girls — or you can shorten it to simply “50 percent.” Even shorter than that, you can use the symbol %, which means percent.

Saying that 50% of the students are girls is the same as saying that of them are girls. Or if you prefer decimals, it’s the same thing as saying that 0.5 of all the students are girls. This example shows you that percents, like fractions and decimals, are just another way of talking about parts of the whole. ...