How many flip-flops are required to construct mod 30 counter ?
Ans. Mod - 30 counter +/- requires 5 Flip-Flop as 30 < 25.
Mod - N counter counts overall ' N ' number of states.
To count 'N' distinguished states we require minimum n FlipFlop's as [N = 2n] For illustration, Mod 8 counter needs 3 Flip-Flop's (8 = 23).