freeCodeCamp/guide/english/certifications/coding-interview-prep/project-euler/problem-6-sum-square-difference/index.md

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title: Sum square difference
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# Problem 6: Sum square difference

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## Problem Explanation
- 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.


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## Solutions
<details><summary>Solution 1 (Click to Show/Hide)</summary>

```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;
}
```

#### Relevant Links

- [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)

</details>