Numerator (Number on top)

The numerator is the upper entry $a$ in a fraction $a/b$. For an integer fraction, it records how many signed units of size $1/b$ are being taken when the denominator is positive: $3/5$ takes three fifths, while $-3/5$ reverses the sign.

A numerator belongs to a chosen representation, rather than being determined by the rational number alone. The equal fractions $3/5$ and $6/10$ have different numerators. The reduced fraction convention makes the numerator and positive denominator unique; zero then has numerator zero and denominator one.