# Duplicate Values in Array - Java

Java Program to Calculate the Sum of Natural Numbers

#### In this example, we will learn to calculate the sum of natural numbers using for loop and while loop in Java.

The positive numbers 1, 2, 3... are known as natural numbers and its sum is the result of all numbers starting from 1 to the given number.

For n, the sum of natural numbers is:

1 + 2 + 3 + ... + n

Example 1: Sum of Natural Numbers using for loop

 public class NaturalNumbers { public static void main(String[] args) {         int num = 100, sum = 0;         for(int i = 1; i <= num; ++i)         {             // sum = sum + i;             sum += i;         }         System.out.println("Sum = " + sum);     } }

When you run the program, the output will be:

Sum = 5050

The above program loops from 1 to the given num(100) and adds all numbers to the variable sum.

We can solve this problem using a while loop as follows:

Example 2: Sum of Natural Numbers using while loop

 public class NaturalNumbers { public static void main(String[] args) {         int num = 75, i = 1, sum = 0;         while(i <= num)         {             sum += i;             i++;         }         System.out.println("Sum = " + sum);     } }

output will be:

Sum = 2850