Twenty percent of $80 is $16. To find out the answer to this problem, the number 80 is multiplied by .2, which is the decimal equivalent of 20 percent.

To calculate a percentage of a number, the percentage should first be converted to a decimal. To do that, the decimal is moved over two spaces to the left. For example, 55 percent is equal to .55. Then the decimal is multiplied by the number to find the answer. When trying to find 20 percent of any number, there is a shortcut method that doubles the original number and then moves the decimal point over one place. Therefore, 80 times 2 equals 160. Moving the decimal one place produces 16. Thus, 20 percent of an $80 check would be $16.