Fractions
Fractions show how many equal parts we have from a whole
Slice a pizza, and we get fractions:
 |
 |
 |
| 1/2 | 1/4 | 3/8 |
|
(One-Half) |
(One-Quarter) |
(Three-Eighths) |
The top number says how many slices we have.
The bottom number says how many equal slices the whole pizza was cut into.
Have a try yourself:
Equivalent Fractions
Some fractions may look different, but are really the same, for example:
| 4/8 | = | 2/4 | = | 1/2 |
| (Four-Eighths) | (Two-Quarters) | (One-Half) | ||
 |
= |  |
= | |
It is usually best to show an answer using the simplest fraction ( 1/2 in this case ). That is called Simplifying, or Reducing the Fraction
Numerator / Denominator
We call the top number the Numerator, it is the number of parts we have.
We call the bottom number the Denominator, it is the number of parts the whole is divided into.
NumeratorDenominator
You just have to remember those names! (If you forget just think "Down"-ominator)
Example: A Pizza Fraction
Imagine we have a pizza sliced into 8 equal parts. But there only 3 slices left.
The fraction of the pizza left is 38
- The numerator is 3 (how many slices left), and
- The denominator is 8 (how many slices the whole pizza was divided into)
Adding Fractions
It is easy to add fractions with the same denominator (same bottom number):
| 1/4 | + | 1/4 | = | 2/4 | = | 1/2 |
| (One-Quarter) | (One-Quarter) | (Two-Quarters) | (One-Half) | |||
|
+ | |
= | |
= | |
Another example:
| 5/8 | + | 1/8 | = | 6/8 | = | 3/4 |
 |
+ |  |
= |  |
= |  |
Adding Fractions with Different Denominators
But what about when the denominators (the bottom numbers) are not the same?
Such as adding slices of pizza that are not the same size:
| 3/8 | + | 1/4 | = | ? |
|
+ | |
= |  |
We must somehow make the denominators the same.
In this case it is easy, because we know that 1/4 is the same as 2/8 :
| 3/8 | + | 2/8 | = | 5/8 |
|
+ |  |
= | |
There are two popular methods to make the denominators the same:
(They both work nicely, use the one you prefer.)
Other Things We Can Do With Fractions
We can also:
Visit the Fractions Index to find out even more.