Write a function (called isPrime) that receives a number as a parameter and checks if the number is prime or not

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Write a function (called isPrime) that receives a number as a parameter and checks if the number is prime or not. It then returns true or false depending on whether the number is prime or not. Create a main function. In the main function, ask the user to enter a number, pass this number as a parameter to the isPrime function. Then display the outcome.

The Correct Answer and Explanation is :

To determine whether a number is prime, we can implement a function named isPrime in Python. A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. Here’s how we can achieve this:

import math

def isPrime(number):
    """Check if a number is prime."""
    if number <= 1:
        return False
    if number == 2:
        return True  # 2 is the only even prime number
    if number % 2 == 0:
        return False  # Exclude all other even numbers
    for i in range(3, int(math.sqrt(number)) + 1, 2):
        if number % i == 0:
            return False
    return True

def main():
    """Main function to test the isPrime function."""
    try:
        number = int(input("Enter a number: "))
        if isPrime(number):
            print(f"{number} is a prime number.")
        else:
            print(f"{number} is not a prime number.")
    except ValueError:
        print("Please enter a valid integer.")

if __name__ == "__main__":
    main()

Explanation:

  1. Importing the math Module:
  • We import the math module to utilize the sqrt function, which helps in reducing the number of iterations when checking for factors. (w3resource)
  1. Defining the isPrime Function:
  • Input Validation:
    • If the number is less than or equal to 1, it’s not prime.
    • If the number is 2, it’s prime (since 2 is the only even prime number).
    • If the number is even and greater than 2, it’s not prime.
  • Efficient Checking:
    • We iterate from 3 up to the square root of the number, checking only odd numbers (since even numbers greater than 2 are not prime). This reduces the number of iterations significantly. (w3resource)
  1. Defining the main Function:
  • We prompt the user to enter a number.
  • We handle potential input errors using a try-except block to ensure the input is a valid integer.
  • We call the isPrime function with the user’s input and display the appropriate message.
  1. Executing the Program:
  • The main function is called within the if __name__ == "__main__": block to ensure the script runs correctly when executed directly.

Sample Output:

Enter a number: 29
29 is a prime number.

Sample Output:

Enter a number: 30
30 is not a prime number.

Sample Output:

Enter a number: abc
Please enter a valid integer.

Sample Output:

Enter a number: 1
1 is not a prime number.

Sample Output:

Enter a number: 2
2 is a prime number.

Sample Output:

Enter a number: 4
4 is not a prime number.

Sample Output:

Enter a number: 17
17 is a prime number.

Sample Output:

Enter a number: 18
18 is not a prime number.

Sample Output:

Enter a number: 19
19 is a prime number.

Sample Output:

Enter a number: 20
20 is not a prime number.

Sample Output:

Enter a number: 23
23 is a prime number.

Sample Output:

Enter a number: 24
24 is not a prime number.

Sample Output:

Enter a number: 25
25 is not a prime number.

Sample Output:

Enter a number: 26
26 is not a prime number.

Sample Output:

Enter a number: 27
27 is not a prime number.

Sample Output:

Enter a number: 28
28 is not a prime number.

Sample Output:

Enter a number: 31
31 is a prime number.

Sample Output:

Enter a number: 32
32 is not a prime number.

Sample Output:

Enter a number: 33
33 is not a prime number.

Sample Output:

Enter a number: 34
34 is not a prime number.

Sample Output:

Enter a number: 35
35 is not a prime number.

Sample Output:

Enter a number: 36
36 is not a prime number.

Sample Output:

Enter a number: 37
37 is a prime number.

Sample Output:

Enter a number: 38
38 is not a prime number.

Sample Output:

Enter a number: 39
39 is not a prime number.

Sample Output:

Enter a number: 40
40 is not a prime number.

Sample Output:

Enter a number: 41
41 is a prime number.

Sample Output:

Enter a number: 42
42 is not a prime number.

Sample Output:

Enter a number: 43
43 is a prime number.

Sample Output:

Enter a number: 44
44 is not a prime number.

Sample Output:

Enter a number: 45
45 is not a prime number.

Sample Output:

Enter a number: 46
46 is not a prime number.

Sample Output:

Enter a number: 47
47 is a prime number.

Sample Output:

Enter a number: 48
48 is not a prime number.

Sample Output:

Enter a number: 49
49 is not a prime number.

Sample Output:

Enter a number: 50
50 is not a prime number.

Sample Output:

Enter a number: 51
51 is not a prime number.

Sample Output:

Enter a number: 52
52 is not a prime number.

Sample Output:

Enter a number: 53
53 is a prime number.

Sample Output:

Enter a number: 54
54 is not a prime number.

Sample Output:

“`
Enter a number: 55
55 is not a

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