code: public static Num percentOf(Object percent, Object ofValue) {
          Num _x = new Num(percent);
          Num _y = new Num(ofValue);
          Calculator cPercent = Calculator.builder().openBracket().val(_x).div(100).closeBracket().mul(_y);
          return cPercent.calculate();
      }
docs: Calculate percent of value
  
  @param percent
  @param ofValue
  @return