A proportion multiplied by 100; SYN. percent, per centum, pct.
Way of representing a number as a fraction of 100. Thus 45 percent (45%) equals 45/100, and 45% of 20 is 45/100 x 20 = 9.
In general, if a quantity x changes to y, the percentage change is 100(x - y)/x. Thus, if the number of people in a room changes from 40 to 50, the percentage increase is (100 x 10)/40 = 25%. To express a fraction as a percentage, its denominator must first be converted to 100— for example, 1/8 = 12.5/100 = 12.5%. The use of percentages often makes it easier to compare fractions that do not have a common denominator.
The percentage sign is thought to have been derived as an economy measure when recording in the old counting houses; writing in the numeric symbol for 25/100 of a cargo would take two lines of parchment, and hence the “100” denominator was put alongside the 25 and rearranged to “%”.