module _97

open System.Numerics

let multiplyLastDigitsFun d =
    let l = System.Math.Pow(10.0,float(d))
    fun (n, m) -> (n * m) % l

let bigPrime =
    let f = multiplyLastDigitsFun 10
    let p = [1..7830457] |> Seq.fold (fun s i -> f(s,2.0)) 1.0
    (28433.0,p) |> f |> (+) 1.0