Fraction

A fraction is a number that shows part of a whole. You write a fraction with two numbers stacked on top of each other, separated by a line. The bottom number tells you how many equal pieces the whole is split into. The top number tells you how many of those pieces you are talking about.

Picture a pizza cut into eight equal slices. If you eat three slices, you have eaten 3/8 of the pizza. The 8 on the bottom is called the denominator. The 3 on top is called the numerator. The denominator names the size of the pieces. The numerator counts them.

Fractions show up everywhere in daily life. A quarter of an hour means 1/4 of 60 minutes, which is 15 minutes. Half a cup of milk in a recipe means 1/2 of a full cup. A baseball player's batting average is really a fraction. So is the score in a basketball game when someone makes 7 out of 10 free throws.

Some fractions are equal to each other even though they look different. The fraction 1/2 is the same amount as 2/4 and 4/8. These are called equivalent fractions. You can find them by multiplying or dividing the top and bottom by the same number. Cutting a sandwich into four pieces and eating two of them gives you the same amount as cutting it in half and eating one piece.

Fractions can be bigger than one whole. The fraction 5/4 means five pieces when the whole was only cut into four. That works out to one whole plus 1/4 left over. Numbers like this are sometimes written as mixed numbers, such as 1 1/4.

People have been using fractions for thousands of years. Ancient Egyptians used fractions more than 4,000 years ago, before most modern countries even existed. They needed them to divide land along the Nile River and to share food fairly. The way we write fractions today, with one number above a line and one below, came from Arab mathematicians in the Middle Ages.

Fractions are also closely related to decimals and percents. The fraction 1/2 is the same as the decimal 0.5 and the percent 50%. They are three different ways of saying the same thing. Once you understand fractions, a lot of math that looks scary later, like algebra and probability, gets much easier to follow.