# How to Create a Prime Number Checker in Python?

You can create a prime number checker in Python using a simple algorithm that checks if a number is divisible only by 1 and itself. Here’s an example code snippet:

``````def is_prime(n):
if n <= 1:
return False
for i in range(2, int(n**0.5) + 1):
if n % i == 0:
return False
return True

# Example usage:
num = 23
if is_prime(num):
print(num, "is a prime number.")
else:
print(num, "is not a prime number.")``````

In this example, we define a `is_prime` function that takes a positive integer `n` as input and returns `True` if `n` is prime, and `False` otherwise.

We first check if `n` is less than or equal to 1, which is not a prime number. If `n` is greater than 1, we use a `for` loop to iterate over all possible divisors of `n` from 2 up to the square root of `n`. We use the `int()` and `**` operators to calculate the square root of `n`.

If we find a divisor of `n` other than 1 or `n` itself, we immediately return `False`, indicating that `n` is not prime. If we have checked all possible divisors up to the square root of `n` without finding any factors, we can conclude that `n` is prime and return `True`.

Finally, we test the function by checking if the number 23 is prime using `is_prime(23)` and print a message accordingly. You can modify this code to check for prime numbers in a range or to input numbers from the user.