In mathematics, fractions are ratios. A fraction represents a proportional relationship between a part or parts and the whole. Some, but not all fractions, can be accurately represented with a combination of whole numbers and decimals. Fractions can be added, subtracted, multiplied and divided.University of Utah: Math 1010 Online

When changing fractions into decimals and percentages, it is necessary to see fractions as division problems. The top number is divided by the bottom number. For more details on this, see How To Convert Fractions.

Many fractions can be represented accurately by quotients, but there are certain numbers, such as pi, that can only be estimated. Pi can be exactly represented as a fraction. The numerator is a circle's circumference and the denominator is a circle's diameter. However, if pi is written out as a quotient of numbers, the decimal places will keep repeating indefinitely.Wolfram MathWorld: Pi Therefore, fractions are very useful ways of accurately representing numbers.