Fractions are a specific type of ratio that compares a part to a whole. Fractions are rational numbers written in the form ab, where the numerator a is the part and the denominator b is the whole.

There are many possible ways of reading fractions, but one universal method is saying a over b. Fractions where a is less than b are called proper fractions. Fractions where a is greater than or equal to b are called improper fractions. Fractions are also another way to write a division of the numerator by the denominator. 18/9=18÷9 A fraction like 189 can be simplified to 21, or just 2. It is important to keep in mind that the denominator of a fraction can never be equal to 0 because the quotient of division by 0 is always undefined.