f# Ex 9

// Exercise 9 – General (… continued from previous – General)
// Queation 5
// Year of

open System

let yearOf(x:int):int=
    let (year400:int) = (x - 1) / (400 * 365 + 97)
    let y = (x - 1) % (400 * 365 + 97)
    let (year100:int) = y / (100 * 365 + 24)
    let z = y % (100 * 365 + 24)
    let (year4:int) = z / (4*365 + 1)
    let w = z % (4*365 + 1)
    let (year1:int) = w / 365

    let mutable year = year400*400 + year100*100 + year4*4 + year1 + 1
    if year = 4 then year <- year - 1

    year

printfn "%i" (yearOf(654415))
Console.ReadKey() |> ignore