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# Java Program to Check Whether a Number is Prime or Not

## Java program to check whether the number is prime number or not :

Prime Number are the whole numbers which have two factors i.e. 1 and the number by itself. Some of the facts for the prime numbers are given below :-

• 0 and 1 are not considered as prime number.
• Except for 0 and 1, a number is either a prime number or a composite number.
• Numbers that have more than two factors are called composite numbers.
• The  1 is neither prime nor composite.
• Except 2, all other even numbers are not prime.

The first 25 prime numbers (all the prime numbers less than 100) are : 2, 3, 5, 7, 11, 13, 17, 19, 23
29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97. ### Working :

Step 1 – Ask the user to enter a number.

Step 2 – Set  count = 0.

Step 3 – Create a loop of i from 1 to number n and increase the value of i after every iteration by 1.

Step 4 – Calculate mod(%) of n by every value of i and check whether the calculated value is equal to 0 or not.

Step 5 – If step-4 gets true then, increase the value of count by 1 and move to the step-3 until the test condition get false.

Step 6 – After getting out of the loop check the value of count is equal to 2 or not.

Step 7- If the value of count is equal to 2 then , the number is Prime, else ,number is not prime.

Step 8 – Print the result.

#### Code in Java :

`//JAVA Program to check whether the number entered by user is Prime or not.import java.util.Scanner;public class prime{                                                               //class declaration        public static void main(String[] args)	{	                                                //main method declaration                Scanner sc=new Scanner(System.in);              //scanner class object creation		System.out.println("Enter a number");		int n = sc.nextInt();			        //taking a number n as input		int count=0;		for(int i = 1 ; i <=n ; i++)			{				if(n % i == 0)				//condition for getting the factors of number n			count=count+1;		}		if(count == 2)		                        //if factors are two then, number is prime else not		System.out.println("Prime Number");		else		System.out.println("Not a Prime Number");		sc.close();		                        //closing scanner class(not mandatory but good practice)	}                                                       //end of main method}                                                               //end of class`

#### Output :

`Enter a number12Not a Prime NumberEnter a number23Prime NumberEnter a number67Prime Number` 