Technical Math For Dummies®

Chapter 9. Decimals: They Have Their Place

In This Chapter

• Looking at the uses of the decimal point and decimal numbers

• Doing math with decimals

• Converting fractions to decimals and decimals to fractions

• Rounding decimals in your work

• Using decimals in change-making and figuring sales tax

Decimal numbers (sometimes just called decimals) are so commonplace that you probably hardly think about them. Like paved roads and running water, they show up every day in your work and your personal life. And like the roads and the water, you would have a hard time getting through a day without them.

You can't escape decimals in the digital age. If you're making doors, moldings, or signs or doing granite or stone work, you have to be an artist, a craftsperson, and a mathematician. The machine shop has used decimal fractions for decades. Also, the lab and the hospital use the metric system extensively, and all metric numbers are decimal numbers. Metric measurement is also increasingly the standard for working with cars and cooking.

Decimals and decimal fractions are easy. In this chapter, you review the names for decimal numbers and their parts, do math with decimals, and perform conversions. You also see handy tips about money and sales tax — all requiring decimal math.

Decimal numbers for modern times

Decimals are modern and precise, and that's what you need in modern times. In the ancient past, builders probably built just by judging the dimensions of stone and wood. Later, they measured, using sticks ...