A decimal number can be transformed into a percentage by multiplying it by 100. If the number is a fraction, it is first necessary to convert it into a decimal by dividing the numerator by the denominator.
A percentage is used to describe how much of something there is compared to another amount. A common example is a piece of a pie. If someone takes a piece that is a quarter of the pie, that is equal to 25 percent of the pie. The total percentage of any one object or number cannot exceed 100 percent. For example, eating the whole pie would be eating 100 percent of the pie.