let euler9 () =
  let result = ref 0 in
  for a = 1 to 333 do
    let num = 500000 - 1000 * a in
    let den = 1000 - a in
    if num mod den = 0 then begin
      let b = num / den in
      if b > a then
        let c = 1000 - a - b in
        if c > b then result := a * b * c
    end
  done;
  !result

;;

euler9 ()