A ratio of two integers, or any number that can be expressed as such a ratio.
A simple fraction is a half:
The value at the top of the fraction is the numerator and the value at the bottom is the denominator:
Fractions can be added together once the fractions being added have a common denominator.
Subtraction of fractions is performed in a similar way to addition.
To multiply fractions, the numerators are multiplied together and the same is done with the denominators.
To divide fractions, the numerator of the dividend is multiplied by the divisor's denominator to form the numerator. The denominator of the dividend is multiplied by the divisor's numerator to form the denominator.
See also: Common Denominator, Division, Divisor, Egyptian Fraction, Farey Sequence, Improper Fractions, Lowest Common Denominator, Lowest Terms, Mixed Numbers, Numerator, Proper Fractions, Real Number, Unit Fraction, Vinculum, Vulgar Fraction.