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