Percentage Functions

A percentage function is a common math function for calculating portions. The percentage function takes the form z is equal to x percent of a number y. Taking a percent can be viewed as the same operation as multiplication by a fraction. If the fraction is a common fraction it is the ratio of the percent portion to the total amount, and if it is a decimal fraction it is one one-hundredth times the percent. If the x variable, which is the percent, is equal to a hundred then the result is just the y variable. If the percent is over a hundred then the result is greater than y. If the percent is less than a hundred than the result is less than y. If the percent is negative than the result is less than zero, unless y is also negative. A percentage is usually not a negative number. Both the domain of the x and y variables, and range of the z variable for the percentage function are considered to be the set of all real numbers.

Percentage functions:
Where z = x% of y,
if x equals 20 percent,
then z equals .2 times y
or z equals one fifth times y.

Where z = x% of y,
if x equals 75 percent,
then z equals .75 times y
or z equals three quarters times y.