30 lines
1.1 KiB
Markdown
30 lines
1.1 KiB
Markdown
|
---
|
||
|
title: Sum square difference
|
||
|
---
|
||
|
## Problem 6: Sum square difference
|
||
|
|
||
|
### Method:
|
||
|
- Sum of first n natural numbers can be calculated by using this formula:
|
||
|
- ![sum of n numbers](https://wikimedia.org/api/rest_v1/media/math/render/svg/99476e25466549387c585cb4de44e90f6cbe4cf2)
|
||
|
|
||
|
- Sum of squares of n natural numbers can be calculated by using this formula:
|
||
|
- ![sum of n squares](https://wikimedia.org/api/rest_v1/media/math/render/svg/ae043bef33d41161541238bdbf4feca9f5e179dd)
|
||
|
|
||
|
- We can calculate the values using the above formula and subtract them to get the result.
|
||
|
|
||
|
### Solution:
|
||
|
```js
|
||
|
function sumSquareDifference(n) {
|
||
|
const sumOfN = (n*(n+1))/2;
|
||
|
const sumOfNSquare = (n*(n+1)*(2*n+1))/6;
|
||
|
|
||
|
//** is exponentaial operator added in ES7, it's equivalent to Math.pow(num, 2)`
|
||
|
return (sumOfN ** 2) - sumOfNSquare;
|
||
|
}
|
||
|
```
|
||
|
- [Run Code](https://repl.it/@ezioda004/Problem-6-Sum-square-difference)
|
||
|
### References:
|
||
|
|
||
|
- [Sum of n numbers - Wikipedia](https://en.wikipedia.org/wiki/1_%2B_2_%2B_3_%2B_4_%2B_%E2%8B%AF)
|
||
|
- [Sum of n square numbers - Wikipedia](https://en.wikipedia.org/wiki/Square_pyramidal_number)
|