private var_type eval_exp13()  throws StopException, SyntaxError {
	  var_type result, partial_value;
	  String op;

	  result = eval_exp14 ();
	  op = token.value;
	  while(op.equals("*") || op.equals("/") || op.equals("%") ){		
		token = lexer.get_token();
		partial_value = eval_exp14();
		
		boolean constant = result.constant && partial_value.constant;
		if(checkOnly && !constant){
			result = result.getReturnTypeFromBinaryOp(op, partial_value);
			return result;
		}
		if(op.equals("*"))
			result = result.mul(partial_value);
		else if(op.equals("/"))
			result = result.div(partial_value);
		else if(op.equals("%"))
			result = result.mod(partial_value);

		op = token.value;
	  }

	  return result;
	}