#### Problem

The sum of the squares of the first ten natural numbers is,

1^{2}+ 2^{2}+ … + 10^{2}= 385

The square of the sum of the first ten natural numbers is,

(1 + 2 + … + 10)^{2}= 55^{2}= 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.

#### Solution

let numbers = [|1..100|] let sumOfSquares = numbers |> Array.map (fun x -> x * x) |> Array.sum let sum = numbers |> Array.sum let squareOfSum = sum * sum let diff = squareOfSum – sumOfSquares

precogtyranthere’s without defining any functions, but same approach.

(List.sum [1..100] |> (fun x -> x*x)) – (List.map (fun x -> x*x)[1..100] |> List.sum)