Here we will proceed it in general suppose we have n boolian variable so for n boolian variable if we draw a k map then it have total 2^n blocks in that k map and in each k map block there are 2 possibilities either 1 or 0 so total combination = (2)^2^n.
Now for r qestion n=4 so we have (2)^2^n.=2^16 boolean expression as well as boolean functions also.