# Prime Number Program in Java

Here, first we understand that what is prime number,

### Prime Numbers

A prime number is a natural number greater than 1, that is divisible by only two numbers: 1 and itself.

For Example: 2, 3, 5, 7,11,13……..are the prime numbers.

```Note: 0 and 1 are not prime numbers.
The 2 is the only even prime number because all the other even numbers can be divided by 2.```

### Problem:

Input :   Enter a number: 17
Output:  17 is a prime number.

### Explanation

This Java program checks if a given number is prime or not. It prompts the user for input, then utilizes a `for` loop to iterate from 2 up to the square root of the number. Within each iteration, it checks if the number is divisible by the current value of `i`. If a divisor is found, it concludes the number is not prime. If no divisors are found, then it’s a prime number.

### Solution:

#### code:

```class PrimeNo{
public static void main(String []args){
int num=7;
int temp=0;
for(int i =2;i<=num-1;i++){
if(num%i==0){
temp=temp+1;
}
}
if(temp==0){
System.out.println(num+" is a prime number");
}
else{
System.out.println(num+" is not prime number ");
}
}
}```
##### Output:
`7 is a prime number`

### Approach 2 : By Using Scanner Class :

```import java.util.Scanner; // import scanner class
class PrimeNo{
public static void main(String []args){
Scanner sc =new Scanner(System.in);  // object of scanner class
int temp=0;
System.out.println("enter any number");
int num = sc.nextInt();
for(int i =2;i<=num-1;i++){
if(num%i==0){
temp=temp+1;
}
}
if(temp==0){
System.out.println(num+" is a prime number");
}
else{
System.out.println(num+" is not prime number ");
}
}
}```
##### Output:
```enter any number
77
77 is not prime number```
##### more java programs for practice:

Java Program to Get Input from User

Find the Greatest of the Two Numbers in Java

Addition of two numbers in java