Python
# Program to check if a number is a power of 2
n = int(input("Enter a positive integer: "))
if n <= 0:
print("Please enter a positive integer.")
else:
while n % 2 == 0:
n //= 2
if n == 1:
print("It is a power of 2")
else:
print("It is not a power of 2")Output
Enter a positive integer: 16 It is a power of 2
We divide by 2 until the number is no longer even; if we eventually get 1, the original number was a power of 2.