Percent means “out of one hundred.” When you say that 25 percent of students in your class wear glasses, you're saying that if there were exactly 100 students, 25 of them would wear glasses. The symbol for percent is %, which you can think of as a little 100 (the 1 and two 0s) tipped on its side.

Percents help us compare things fairly, no matter how big or small the groups are. If your teacher says you got 90 percent on a spelling test, that means you got 90 out of every 100 points possible, whether the test had 10 words, 20 words, or 50 words. If a weather forecast says there's a 30 percent chance of rain, meteorologists are saying that in 100 similar weather situations, it would rain in about 30 of them.

You'll see percents everywhere: stores advertise “50% off” sales, phone batteries show their charge as a percent, and sports statistics track what percent of shots a basketball player makes. Understanding percents helps you see proportions clearly and compare different situations on equal terms.