Java Program to Find Sum of Natural Numbers

The natural numbers are the numbers that include all the positive integers from 1 to infinity. For example, 1, 2, 3, 4, 5, ......, n. When we add these numbers together, we get the sum of natural numbers.

In this section, we will create the following programs:

• Java program to find the sum of the first 100 natural numbers
• Java program to find the sum of n natural numbers
• Java program to find the sum of n natural numbers using the function

We can also find the sum of n natural number using the mathematical formula:

Suppose, we want to find the sum of the first 100 natural numbers. By putting the value in the above formula, we get:

In this section, we are going to use the following ways to find the sum of natural numbers.

• Using Java for Loop
• Using Java while Loop
• Using Function

Using Java for Loop

Using Java for loop is the easiest way to find the sum of natural numbers.

SumOfNaturalNumber1.java

Output:

Sum of First 10 Natural Numbers is = 55

Using Java while Loop

In the following example, we have replaced the for loop with the while loop. The while loop executes until the condition i <= num do not become false. It calculates the sum of natural numbers up to a specified limit.

SumOfNaturalNumber2.java

Output:

Sum of First 100 Natural Numbers is = 5050

Sum of n Natural Numbers

The following program finds the sum of n natural numbers. In this program, we have used the same while loop, as we have used in the above program. We have also taken two inputs from the user i.e. i and num. The variable i is the starting number and the variable num is the end number. For example, if we want to find the sum of natural numbers from 20 (i) to 100 (num).

SumOfNaturalNumber3.java

Output:

Sum from: 1
Sum up to: 1000
Sum of Natural Numbers = 500500

Using Function

In the following program, we have found the sum of n natural number using the function.

SumOfNaturalNumber4.java

Output:

Sum of Natural Numbers is: 1275

Let's see another program.

In the following program, we have used the formula to find the sum of natural numbers.

SumOfNaturalNumber5.java

Output:

Sum of Natural Number is: 20100