# Numerator

Numerator[expr]

gives the numerator of expr.

# Details and Options • Numerator picks out terms which do not have superficially negative exponents. Denominator picks out the remaining terms.
• An exponent is "superficially negative" if it has a negative number as a factor.
• The standard representation of rational expressions as products of powers means that you cannot simply use Part to extract numerators.
• Numerator can be used on rational numbers.

# Examples

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## Basic Examples(1)

Extract the numerator of a rational number:

Extract the numerator of a rational expression:

## Scope(7)

Rational numbers:

Gaussian rationals:

Rational expressions:

Select terms without syntactically negative exponents:

All exponents syntactically negative:

No syntactically negative exponents:

## Options(2)

### Modulus(1)

Find numerators over integers modulo :

### Trig(1)

Numerators of trigonometric functions:

## Properties & Relations(4)

Denominator gives the terms with negative exponents:

An expression is a quotient of its numerator and denominator:

Use Cancel to cancel common factors between the numerator and the denominator:

Together writes an expression as a fraction and cancels common terms:

Introduced in 1988
(1.0)