Design a combination circuit which can detect prime numbers from 0 to 15?
Procedure:


Identify all the prime numbers between 0 and 15 (2, 3, 5, 7, 11,
13).
Determine how many bits you need for a maximum value of 15
(four bits).
Construct a Karnaugh map of the appropriate size and mark all prime numbers as logical 1 and all non-primes as logical 0.
Reduce the Karnaugh map to find your logic function.


I'll leave you to do the grunt work yourself.