5.8.2 Numerator and denominator

The numerator and denominator of an expression can be obtained with

ex ex::numer();
ex ex::denom();
ex ex::numer_denom();

These functions will first normalize the expression as described above and then return the numerator, denominator, or both as a list, respectively. If you need both numerator and denominator, calling numer_denom() is faster than using numer() and denom() separately.