Denominator of a fraction after simplification : denom getDenom

denom or getDenom takes as argument a fraction and returns the denominator of this fraction after simplification (for rational fractions see 1.28.4).
Input :

denom(42/12)

Or :

getDenom(42/12)

Output :

2

To avoid simplifications, the argument must be quoted (for rational fractions see 1.28.3).
Input :

denom('42/12')

Or :

getDenom('42/12')

Output :

12