# Java Program to display the sum of first N natural numbers

In this post, we will write two java programs to Sum of first N natural numbers. Positive integers 1,2,3,4, etc are known as natural numbers.

## How the program will work?

• The first program will take input of N number from the user.
• After getting value N than calculates the sum using loop.

To understand these programs you should be knowledge of following Java concepts:

• Java For loop
• Java While loop

### Example:

1. Input1:
2. Enter the value of n: 20
3. Output:1
4. Sum of the first 20 natural number is: 210
1. Input2:
2. Enter the value of n: 10
3. Output2:
4. Sum of the first 10 natural number is: 55

## Example 1: Program to calculate the sum of N natural numbers using for loop

This program asks the user to enter the value of N then run the for loop till N number and add each value till loop get a break. And at the end display the addition of N numbers. In for Loop, first of all, the loop checks the condition and then enter to loop. If the number validated the condition then starts increment in the loop.

```import java.util.Scanner;

public class demo {
public static void main(String[] args) {
Scanner sc= new Scanner(System.in);
System.out.print("Enter the value of n:");
int N = sc.nextInt();
int sum=0;

for (int i=0;i<=N;i++){
sum += i;
}
System.out.println("Sum of the first "+N+" natural number is: "+sum);
}
}```

### Output:

```Enter the value of n: 30
Sum of the first 30 natural number is: 465```

## Example 2: Program to calculate the sum of N natural numbers using while loop

In this program, we will use while loop to calculate the sum of N natural number. While loop first of all check condition and then enter in a loop. At last, it increments the value.

```import java.util.Scanner;
public class sum_of_natural_number {
public static void main(String[] args) {
Scanner sc= new Scanner(System.in);
System.out.print("Enter the value of n:");
int N = sc.nextInt();
int sum=0;
int i=1;

while (i<=N){
sum +=i;
i++;
}
System.out.println("Sum of the first "+N+" natural number is: "+sum);
}
}```

### Output:

```Enter the value of n:20
Sum of the first 20 natural number is: 210```