- $"N"$ Flip Flops $= "2^N"$ number of states in Asynchronous counter $= "mod \:2^N"$ Asynchronous counter.
- $"2^N"$ number of states in Asynchronous counter we required $"N"$ flip flops.
- $"N"$ number of states in Asynchronous counter we required $"\left \lceil \log_{2} N\right \rceil"$ flip flops.
Here mod $2^{4}$ counter, so we required $4$ flip flops.