This is documentation for Mathematica 6, which was
based on an earlier version of the Wolfram Language.
View current documentation (Version 11.2)

Denominator

Denominator[expr]
gives the denominator of expr.
  • Denominator picks out terms which have superficially negative exponents. Numerator picks out all 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 denominators.
New in 1