Denominator of a fraction after simplification

The denom or getDenom command finds the denominator of a fraction.

denom takes r, a fraction.
denom(r) returns the denominator of r after it has been reduced to lowest terms. (For rational expressions see Section 11.6.4).

denom(42/12)

or:

getDenom(42/12)

To avoid simplification, the argument must be quoted (see Section 9.1.4).

(For rational expressions see Section 11.6.3).

denom('42/12')

or:

getDenom('42/12')