public function normalizeNumber($p_num, $p_dec = null)
    {
        if (is_null($p_dec)) {
            $p_dec = $this->decimalPoint;
        }
        $normalized = preg_replace('/[^-'.preg_quote($p_dec).'0-9]/', '', $p_num);
        // Verify numbers are equal....
        $mn1 = floatval($p_num);
        $mn2 = floatval($normalized);
        if ($mn1 != $mn2) {
            throw new NumbersWordsException(sprintf('number conversion error : %s <> %s', $p_num, $mn2));
        }

        return $normalized;
    }