add a solution for Project Euler problem #006

Project-Euler/Problem006.js

@@ -0,0 +1,24 @@
+/*
+Sum square difference
+The sum of the squares of the first ten natural numbers is 385,
+
+The square of the sum of the first ten natural numbers is 3025,
+
+Hence the difference between the sum of the squares of the first ten natural numbers and the square of the sum is 3025 - 385 = 2640.
+
+Find the difference between the sum of the squares of the first one hundred natural numbers and the square of the sum.
+*/
+
+const findSumSquareDifference = (elementsCount) => {
+  const naturalNumbers = Array(elementsCount).fill().map((_, i) => i + 1)
+
+  let sumOfSquares = 0
+  naturalNumbers.forEach(number => { sumOfSquares += Math.pow(number, 2) })
+
+  const sumOfNumbers = naturalNumbers.reduce((prev, current) => { current += prev }, 0)
+  const squareOfSums = Math.pow(sumOfNumbers, 2)
+
+  return squareOfSums - sumOfSquares
+}
+
+console.log(findSumSquareDifference(20))