For example: the input frequency of SR flip flop is 10 kHz, the output frequency is 5 kHz. This I know because its simple. Output (q) toggles at every half of the time period T, so fo = fin/2. But when it comes to harder circuits (such as mod N counters), is there a generic method or formula to calculate the output frequency. Can anyone please send a relevant link from where I can know more about this.