code: public static BigDecimal rounddown(EvaluationContext ctx, Object number, Object numDigits) {
          BigDecimal _number = Conversions.toDecimal(number, ctx);
          int _numDigits = Conversions.toInteger(numDigits, ctx);
  
          return ExpressionUtils.decimalRound(_number, _numDigits, RoundingMode.DOWN);
      }
docs: Rounds a number down, toward zero