The denominator is usually ignored or in some cases is ordered according to size if there are multiple numerators of the same size. (teachermagazine.com.au)
Update: Annual growth percents plotted are calculated using prior year measurement as numerator and following year measurement as denominator. (c3headlines.com)
In risk free rate formula below why is 1 added on numerator and denominator and the value is substracted by 1 Rf = (1 + nominal risk free rate) / (1 + inflation)-1 (money.stackexchange.com)