# Python Program To Check Prime Number

Python programming is one of the most popular programming languages that is used in the latest technology. A beginner in any programming languages would have come across initial practice exercises such as identifying prime numbers, even or odd numbers, etc. In this article, we will learn how to write a prime number program in Python to check whether a number entered by the user is a prime number or not.

To write this program, firstly, we need to understand what a prime number is. A prime number is a natural number that is only divisible by 1 and itself, which means that this number cannot be a product of any other smaller two numbers. For example, 2, 3, 7, 11, 13, 17, etc. are prime numbers.

The program has to check if the number is divisible by any of the numbers lying in between 2 and itself. If it is divisible by any of these numbers, the remainder will be zero, and we can conclude that it is not a prime number. And if the remainder is not zero, then it is a prime number.

## Python Programming Topics

There are three Python programming topics that one should know to be able to write the prime number program in Python. These are:

### 1. If…else statement

This is used when there is a need to decide whether to execute a particular set of codes or no. It depends on the condition. If the condition is satisfied, i.e., the test expression is true, then the statements will be executed. If the condition is not satisfied, the statements will not be executed, and it will jump to the ‘else’ section of the code.

if test expression:

Body inside if

else:

Body inside else

A simple example better explains this:

#To check if the number is positive and print accordingly

num = 5

if num > 0

print(“Number is Positive)

else

print(“Number is Negative)

Output: Number is positive

### 2. For loop

The For loop is used to iterate over a sequence. So, for each item in the list or set, a set of statements can be executed.

for variable in sequence:

Body inside for

For example:

sports = [“cricket”, “football”, “tennis”]

for z in sports:

print(z)

Output: cricket

football

tennis

### 3. Break

The break statement can change the flow of a loop in Python. Usually, a loop repeats over a sequence of codes continuously till the condition is not satisfied or the test expression is false. But sometimes, we may want to stop the current iteration of a loop or maybe the whole loop by checking for one condition. In such cases, a break statement is used.

for variable in sequence:

if condition:

break

The loop will be broken once the condition is satisfied.

To understand better with an example:

for var in “mango”:

if var == “g”:

break

print(var)

Output: m

a

n

## Prime Number Program In Python

In this program, we will first ask the user to enter a number. After that, we will check if the number is greater than 1. If it is, we will check if it is divisible by any number between 2 and itself. If it is divisible, then it prints that the number is not a prime number. If it is not divisible, then it prints that the number is a prime number. And if the number is less than 1, then it prints that the number is not a prime number.

The Python program is as follows:

num = int(input(“Enter a number: “))

if num > 1:

for i in range(2, num):

if (num % i) == 0:

print(num, “is not a prime number”)

break

else:

print(num, “is a prime number”)

else:

print(num, “is not a prime number”)

The int() statement is used to convert any number entered by the user into an integer. The range() statement is used so that the value of “i” goes through each number from 2 to the number entered by the user. The print() statement is used to print the value inside the bracket into the output. The user can now check whether any number entered by them is a prime number or no.

## Conclusion

This article demonstrates how to write a simple program for a prime number in Python language. Using this logic, we can write other basic programs to improve our skills. And we have also learned three programming topics, i.e., if..else statement, for loop, and break. These are basic topics that can be used for more complicated and long programs to execute larger tasks to understand a prime number in Python

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