# 1. Introduction

Natural numbers are a part of number system which includes all the positive integers from 1 till infinity and are used for counting. In this Java program, we are going to find the sum of natural numbers using a *while* loop. This is a fundamental example showcasing the usage of loops and conditional statements in Java.

# 2. Program Steps

1. Define a class named *SumOfNaturalNumbers*.

2. Inside the *main* method, define an integer *num* up to which we want to calculate the sum.

3. Initialize two variables *sum* and *i* to 0. *sum* will hold the final result, and *i* is our counter variable.

4. Use a *while* loop to iterate until *i* is less than or equal to *num*.

5. In each iteration, add the value of *i* to *sum*.

6. Increment the value of *i* in each iteration.

7. After exiting the loop, print the value of *sum*.

# 3. Code Program

```
public class SumOfNaturalNumbers { // Step 1: Define a class named SumOfNaturalNumbers
public static void main(String[] args) { // Main method
int num = 100; // Step 2: Define an integer num up to which we want to calculate the sum
int sum = 0; // Step 3: Initialize sum to 0
int i = 1; // Step 3: Initialize counter variable i to 1
// Step 4: Use a while loop to iterate until i is less than or equal to num
while (i <= num) {
sum = sum + i; // Step 5: In each iteration, add the value of i to sum
i++; // Step 6: Increment the value of i in each iteration
}
// Step 7: Print the value of sum
System.out.println("Sum of Natural Numbers up to " + num + " is: " + sum);
}
}
```

### Output:

Sum of Natural Numbers up to 100 is: 5050

# 4. Step By Step Explanation

– *Step 1:* We define a class named *SumOfNaturalNumbers*.

– *Step 2:* Inside the *main* method, we define an integer *num* up to which we want to calculate the sum. In this example, we have taken *num* as 100.

– *Step 3:* We initialize two variables *sum* and *i* to 0 and 1 respectively. *sum* will hold the final result, and *i* is our counter variable.

– *Steps 4 to 6:* We use a *while* loop to iterate until *i* is less than or equal to *num*. In each iteration, we add the value of *i* to *sum* and increment the value of *i*.

– *Step 7:* After exiting the loop, we print the value of *sum*, which holds the sum of natural numbers up to *num*.