Java Program to find Sum of Natural Numbers

Java Program to find Sum of Natural Numbers

The positive integers 1, 2, 3, 4 etc. are known as natural numbers. Here we will see three programs to calculate and display the sum of natural numbers.
  • First Program calculates the sum using while loop
  • Second Program calculates the sum using for loop
  • Third Program takes the value of n(entered by user) and calculates the sum of n natural numbers.
To understand these programs you should be familiar with the following concepts of Core Java Tutorial:
  • Java For loop
  • Java While loop

Example 1: Program to find the sum of natural numbers using while loop

public class Demo {

public static void main(String[] args) {

int num = 10, count = 1, total = 0;

while(count <= num)
{
total
= total + count;
count
++;
}

System.out.println("Sum of first 10 natural numbers is: "+total);
}
}
Output:
Sum of first 10 natural numbers is: 55

Example 2: Program to calculate the sum of natural numbers using for loop

public class Demo {

public static void main(String[] args) {

int num = 10, count, total = 0;

for(count = 1; count <= num; count++){
total
= total + count;
}

System.out.println("Sum of first 10 natural numbers is: "+total);
}
}
Output:
Sum of first 10 natural numbers is: 55

Example 3: Program to find sum of first n (entered by user) natural numbers

import java.util.Scanner;
public class Demo {

public static void main(String[] args) {

int num, count, total = 0;


System.out.println("Enter the value of n:");
//Scanner is used for reading user input
Scanner scan = new Scanner(System.in);
//nextInt() method reads integer entered by user
num
= scan.nextInt();
//closing scanner after use
scan
.close();
for(count = 1; count <= num; count++){
total
= total + count;
}

System.out.println("Sum of first "+num+" natural numbers is: "+total);
}
}
Output:
Enter the value of n:
20
Sum of first 20 natural numbers is: 210

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