Purplemath
Percentages refer to fractions of a whole; that is, whatever you're looking at, the percentage is how much of the whole thing you have. For instance, "50%" means "\frac{1}{2}
2
1
"; "25%" means "\frac{1}{4}
4
1
"; "40%" means "\frac{2}{5}
5
2
"; et cetera.
Often you will need to figure out what percentage of something another thing is. For instance, if a class has 26 students, and 14 are female, what percentage of the students are female? It is 14 out of 26, or \frac{14}{26}
26
14
= 0.538461538462..., which is about 54%. (For more information on "percent" word problems, look at the Percent of lesson.)
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Converting Decimals, Fractions, and Percents on MathHelp.com
Decimals and Percents
"Percent" is actually "per cent", meaning "out of a hundred". (It comes from the Latin per centum for "thoroughly hundred".) You can use this "out of a hundred" meaning, along with the fact that fractions are division, to convert between fractions, percents, and decimals.