gistfile1.fs

let rec dividesIntoAllUpTo (n: int) (d: int) =
    match d with 
    | 1 -> true
    | _ -> (n % d = 0) && (dividesIntoAllUpTo n (d - 1))

let matchesCriteria n = 
    dividesIntoAllUpTo n 20

let main = 
    let current_num = ref 20
    while true do   
        if (not (matchesCriteria !current_num)) then 
            current_num := !current_num + 20
        else 
            printfn "%i matches criteria!" !current_num
            ignore (System.Console.ReadLine())
            exit(0)
    done