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.


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Basic Examples  (3)

Extract the numerator of a rational number:

Extract the numerator of a rational expression:

Extract the numerator of a symbolic expression:

Scope  (9)

Rational numbers:

Gaussian rationals:

Rational expressions:

Select terms without syntactically negative exponents:

All exponents syntactically negative:

No syntactically negative exponents:

Numerator automatically threads over lists:

Compute the numerator over the integers modulo 5:

Compute the numerator while incorporating common trigonometric identities:

Options  (2)

Modulus  (1)

Find numerators over integers modulo :

Trig  (1)

Numerators of trigonometric functions:

Applications  (2)

Explore patterns in reduced rational numbers:

View the occurrences of integers as the numerator in reduced rational numbers:

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:

Wolfram Research (1988), Numerator, Wolfram Language function,


Wolfram Research (1988), Numerator, Wolfram Language function,


@misc{reference.wolfram_2020_numerator, author="Wolfram Research", title="{Numerator}", year="1988", howpublished="\url{}", note=[Accessed: 18-January-2021 ]}


@online{reference.wolfram_2020_numerator, organization={Wolfram Research}, title={Numerator}, year={1988}, url={}, note=[Accessed: 18-January-2021 ]}


Wolfram Language. 1988. "Numerator." Wolfram Language & System Documentation Center. Wolfram Research.


Wolfram Language. (1988). Numerator. Wolfram Language & System Documentation Center. Retrieved from