The minimum number of Flip-Flops required to construct a binary Modulo $n$ counter is ________

n flip flops can be used to make modulo 2^{n } counter.

So according to the question the answer must be ceil(log_{2}(n))

binary modulo n means the possible no.of states = n and mark them as 0,1,2,3,....n-1.

therefore you need to indicate n states with k flipflops

if n=2^{p }then k=p

if n $\neq$ 2^{p} then k= ⌈log_{2}n⌉