Lesson: Chapter - 4

Percents

A percent is another way to describe a part of a whole (which means that percents are also another way to talk about fractions or decimals). Percent literally means “of 100” in Latin, so when you attend school 25 percent of the time, that means you only go to school ²⁵/ ₁₀₀ of the time (or .25).

You would probably fail all your classes if your attendance percentage was that low, so don’t get any ideas from our example. Instead, take a look at this question: 3 is what percent of 15?

This question presents you with a whole, 15, and then asks you to determine how much of that whole 3 represents in percentage form. Since a percent is “of 100,” to solve the question you have to set the fraction ³/ ₁₅ equal to ^x/₁₀₀:

You then cross-multiply and solve for x:
15 x = 3 × 100 = 300
x= 20

Converting Percents into Fractions or Decimals

You should be skilled at converting percents into fractions and decimals, because these problems will definitely come up on the Math IC test.

Percents relate to decimal numbers very simply and directly. A percent is a decimal number with the decimal point moved two decimal places to the left.

For example:
50 % of 12 = .50 × 12 = 6
12 % of 120 = .12 × 120 = 14.4

To convert from a decimal number to a percent, move the decimal point two places to the right:

.07 × 1100 = 7 % of 1100 = 77
.97 × 13 = 97 % of 13 = 12.61

On an even more simplistic level, we can just say that 50% = .5 or 22.346% = .22346. Percentages greater than 100 exist, too. 235% = 2.35, for example.

To convert from a percent to a fraction, take the percentage number and place it as the numerator over the denominator 100. 58 percent is the same as ⁵⁸/ ₁₀₀

To convert from a fraction back to a percent, the easiest method is to convert the fraction into a decimal first and then change the resultant decimal into a percent.

Next to display next topic in the chapter.

Mathematics Practice Questions