sc1

(* the AC/DC said n is in [100;1000[ *)
let mystery_func n =
  if ((n > 99) && n < (1000)) then
    let hundreds = (n / 100) and tens = ((n/10) mod 10) and units =(n mod 10) in

    if (hundreds + tens + units) < 10 then
        let prod_2_first = (hundreds * tens) in
          (prod_2_first < units) && (tens = (units - hundreds))
      else
        false
  else
    invalid_arg ((string_of_int(n))^" is not a three digits positive int");;
let forAll n  =
  string_of_int(n)^": "^string_of_bool(mystery_func(n))^(
    if (n < 999) then
      forAll(n+1)
    else
      ""
  )