Percent means per one hundred, hence expressing a fractional or mixed number quantity as a percent is the same as converting that quantity to a fraction with a denominator of 100. Thus, a percent signifies the number of parts per 100 being considered. In general,

For example, 4% ? 4/100.

Notice that 100% ? 100/100 = 1. That is, one whole equals 100 percent. Any number less than one whole represents a quantity less than 100 percent and any number greater than one whole represents a quantity greater than 100 percent. Percent can also be expressed as a decimal fraction. Converting a percent to this form is usually easier than converting it to a common fraction.

Becoming proficient with percents involves the ability to readily convert between percents, common fractions, and decimal fractions.

5.1 Working with Percents

Converting a Common Fraction to a Percent

Many times common fractions need to be expressed in percent form. For example, a civil engineer might plan a road elevation change of 1 foot in height for every 10 feet of distance. This amounts to a 10 percent incline, or a 10% grade. The common fraction 1/10 is converted to 10 percent by recalling that a percent can be thought of as a fraction with 100 as the denominator. Raising 1/10 to an equivalent fraction with a denominator of 100 by multiplying it, top and bottom, by 10 results in a percent:

Fractions like this whose denominators are factors of 100 are easy...