# Happy Number Program in Java

## A happy number is a natural number in a given number base that eventually reaches 1 when iterated over the perfect digital invariant function for. Those numbers that do not end in 1 are -unhappy numbers.

``````import java.util.Scanner;

public class HappyNumber
{
public static void main(String[] args)
{
int n, r = 1, num, sum = 0;
Scanner sc = new Scanner(System.in);
System.out.print("Enter number=");
n = sc.nextInt();
num = n;
while (num > 9)
{
while (num > 0)
{
r = num % 10;
sum = sum + (r * r);
num = num / 10;
}
num = sum;
sum = 0;
}
if (num == 1)
{
System.out.println("Happy Number");
}
else
{
System.out.println("Not Happy Number");
}
}
}
``````

#### Output:

```Enter number=31
Happy Number```
##### What is Happy Number?
A happy number is a natural number in a given number base that eventually reaches 1 when iterated over the perfect digital invariant function for. Those numbers that do not end in 1 are -unhappy numbers.

##### What is Happy Number in Java?
A happy number is a natural number in a given number base that eventually reaches 1 when iterated over the perfect digital invariant function for. Those numbers that do not end in 1 are -unhappy numbers.

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