Python program to check prime number

A prime number is a natural number greater than one that has no positive divisors other than one and itself. In other words, a prime number is a number that cannot be evenly divided by any different number except one and the number itself.

For example, some prime numbers are:

2
3
5
7
11
13
17

Prime numbers have important mathematical properties and are used in various fields, including number theory, cryptography, and computer science. They play a crucial role in many algorithms and mathematical concepts.

Sample Python program to check prime number

Here is a simple code to check whether the number entered by user is a Prime number or not.

def is_prime(n):
    if n <= 1:
        return False
    if n <= 3:
        return True
    if n % 2 == 0 or n % 3 == 0:
        return False
    i = 5
    while i * i <= n:
        if n % i == 0 or n % (i + 2) == 0:
            return False
        i += 6
    return True

# Input from the user
num = int(input("Enter a number: "))

if is_prime(num):
    print(num, "is a prime number.")
else:
    print(num, "is not a prime number.")

Python program to check prime numbers from a list

An updated Python code, extended to check whether each number entered is a prime number or not.

def is_prime(n):
    if n <= 1:
        return False
    if n <= 3:
        return True
    if n % 2 == 0 or n % 3 == 0:
        return False
    i = 5
    while i * i <= n:
        if n % i == 0 or n % (i + 2) == 0:
            return False
        i += 6
    return True

# Input from the user
num_list = input("Enter a list of numbers separated by spaces: ").split()
num_list = [int(num) for num in num_list]

for num in num_list:
    if is_prime(num):
        print(num, "is a prime number.")
    else:
        print(num, "is not a prime number.")