 # JavaScript Program To Find Sum Of N Numbers

In this tutorial, you’ll learn how to write a JavaScript program to find sum of N numbers. Sum of N numbers means sum of numbes from 1 to n (n can be 100, 200 etc.)

## Traditional Approach To Find Sum Of N Numbers

Let’s start by writing a simple JavaScript function which will loop through numbers from 1to N and calculate the sum. Here is how it looks :

``````/*
** Method to Find Sum of N Numbers
*/
function findSum(n) {
let result = 0;
for(let i = 1; i <= n; i++) {
result = result + i;
}
return result
}

let n = 10;
console.log(`Sum of numebers from 1 to \${n} is \${findSum(n)}`)``````

As seen in the above, you iterated from 1 to number N and added the numbers to get the sum. The problem with the above implementation is that as the number gets bigger, so does the number of iterations.

## Mathematical Approach To Find Sum Of N Numbers

Using a mathematical approach to find the sum of N numbers may completely remove the use of for loop. Let’s try to address the above problem from a mathematical approach.

The problem that you are trying to solve is :

1 + 2 + 3 + 4 + 5 + 6 + …….. + n

Let’s assume the sum of the above series to be sum.

sum = 1 + 2 + 3 + 4 + 5 + 6 + …….. + n      ——— eq-1

Now let’s reverse the series, and add the numbers backwards which will also give the same sum.

sum = n + (n-1) + (n-2) + (n-3) + (n-4) + ……. + 1     ——- eq-2

Let’s add the above eq-1 and eq-2 equations.

2(sum) = (n+1) + (n+1) + (n+1) + (n+1) + ……. (n+1)

2(sum) = n times (n+1)

sum = (n times (n+1)) / 2

You can use the above formula to find the sum of N numbers. Now let’s write the JavaScript program which implements the above formula.

``````function findSumWithFormula(n) {
return (n * (n + 1)) / 2
}

let n = 10;
console.log(`Sum of numbers from 1 to \${n} is \${findSumWithFormula(n)}`);``````

## Wrapping It Up

In this tutorial, you learnt about two ways to implement the sum of N numbers using JavaScript. Do let us know your thoughts in the comments below.