# Program to find a number is power of 4 or not

**Method 1 .**

A simple method is to take log of the given number on base 4, and if we get an integer then number is power of 4.

**Method 2.**

Another solution is to keep dividing the number by 4, i.e, do n = n/4 iteratively. In any iteration, if n%4 becomes non-zero and n is not 1 then n is not a power of 4, otherwise n is a power of 4.

**Algorithm :**

/* Function to check if x is power of 4*/ bool isPowerOfFour(int n) { if(n == 0) return 0; while(n != 1) { if(n%4 != 0) return 0; n = n/4; } return 1; } int main() { int test_no = 64; if(isPowerOfFour(test_no)) printf("%d is a power of 4", test_no); else printf("%d is not a power of 4", test_no); getchar(); }

**Method 3 :**

A number n is a power of 4 if following conditions are met.

a) There is only one bit set in the binary representation of n (or n is a power of 2)

b) The count of zero bits before the (only) set bit is even.

For example: 16 (10000) is power of 4 because there is only one bit set and count of 0s before the set bit is 4 which is even.