What is a fraction?

What are fractions for?

A fraction is used to represent a part of a whole. When you divide a pizza into 4 equal slices and eat 3 of them, you have eaten 3/4 of the pizza.

A fraction is always written in the form a/b, where:

• a is the numerator: the number of parts you take.
• b is the denominator: the total number of parts in the whole (b can never be equal to 0).

Reading a fraction

Fraction	Reading
1/2	half
1/3	a third
1/4	a quarter
3/4	three-quarters
5/6	five-sixths

Practical example

Imagine a bar of chocolate cut into 6 identical squares. If you eat 2 squares, you have eaten 2/6 of the bar. The denominator (6) indicates the total number of squares, the numerator (2) indicates how many you have taken.

A common pitfall to avoid

Don’t confuse the numerator and the denominator: the denominator is always at the bottom and represents the whole that has been divided; it doesn’t change whether you take more or fewer pieces. Only the numerator varies depending on the quantity taken.

Another common pitfall: a fraction such as 5/4 is perfectly valid, even though the numerator is greater than the denominator. This simply means that there is more than one whole unit (5/4 = 1 whole unit + 1/4).