Numerator[expr]
gives the numerator of expr.


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
open all close allBasic Examples (3)
Scope (9)
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)
Applications (2)
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:
Tech Notes
Related Guides
History
Introduced in 1988 (1.0)
Text
Wolfram Research (1988), Numerator, Wolfram Language function, https://reference.wolfram.com/language/ref/Numerator.html.
CMS
Wolfram Language. 1988. "Numerator." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/Numerator.html.
APA
Wolfram Language. (1988). Numerator. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/Numerator.html
BibTeX
@misc{reference.wolfram_2025_numerator, author="Wolfram Research", title="{Numerator}", year="1988", howpublished="\url{https://reference.wolfram.com/language/ref/Numerator.html}", note=[Accessed: 08-August-2025]}
BibLaTeX
@online{reference.wolfram_2025_numerator, organization={Wolfram Research}, title={Numerator}, year={1988}, url={https://reference.wolfram.com/language/ref/Numerator.html}, note=[Accessed: 08-August-2025]}