If (2p+ 1) is a prime number, which one of the following digits could be the value of p?

Question: If (2^p + 1) is a prime number, which one of the following digits could be the value of p?

Solution:
In such questions, each alternative should be tried.

So, if P = 3, we will get; 8 + 1= 9

If P = 4, we will get; 16 + 1 = 17

If P = 5, we will get; 32 + 1 = 33

If P= 6, we will get; 64 + 1= 65

Out of the four results, only 17 is the prime number. So, the required value of the P is 4.