Glossary
Fraction
Also written: fractions · common fraction
Definition
A fraction names a number of equal parts of a whole. It is written as one number over another, and the bar between them means divide.
The parts of one
The denominator says the whole was cut into four equal parts. The numerator says you have three of them.
The word “equal” is doing real work. Four pieces of different sizes are not quarters.
Three things one fraction means
| Reading | Example |
|---|---|
| parts of a whole | three of four equal slices |
| a point on a number line | the third tick of four between and |
| a division |
All three describe the same number. The division reading is the one that turns a fraction into a decimal, and the number-line reading is the one that makes it a number rather than a shape. See fractions on a number line.
Names by size
- Proper: numerator smaller than denominator, so less than — .
- Improper: numerator at least as big, so or more — .
- Unit fraction: numerator of — . These are the building blocks, since is three of them.
Many names for one amount
Any fraction can be written endlessly many ways.
That flexibility is what lets you give two fractions a shared denominator before adding them. See equivalent fractions.
Lessons that use this term
- Equivalent Fractions: Same Amount, Different Numbers
What equivalent fractions are, how to find them by multiplying or dividing top and bottom by the same number, and how to check two fractions are equal.
- Fractions on a Number Line: Plotting and Reading Them
How to place a fraction on a number line by splitting each whole into equal parts, how to read one off, and why the number line makes fractions easier to order.
- Converting Fractions to Decimals and Back
Two ways to turn a fraction into a decimal, how to tell in advance whether it will terminate or repeat, and how to convert a decimal back into a fraction.