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

34\frac{3}{4}

The denominator 44 says the whole was cut into four equal parts. The numerator 33 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

ReadingExample
parts of a wholethree of four equal slices
a point on a number linethe third tick of four between 00 and 11
a division3÷4=0.753 \div 4 = 0.75

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 1134\tfrac{3}{4}.
  • Improper: numerator at least as big, so 11 or more — 74\tfrac{7}{4}.
  • Unit fraction: numerator of 1114\tfrac{1}{4}. These are the building blocks, since 34\tfrac{3}{4} is three of them.

Many names for one amount

Any fraction can be written endlessly many ways.

12=24=50100\frac{1}{2} = \frac{2}{4} = \frac{50}{100}

That flexibility is what lets you give two fractions a shared denominator before adding them. See equivalent fractions.

Lessons that use this term

Related terms