function getMax() {
          var args = Array.prototype.slice.call(arguments, 0);


          return Math.max.apply(null, args.map(item => {
              var arr = item.toString().split('.');
              return arr.length > 1 ? arr[1].length : 0;
          }));
      }


      function add() {
          var args = Array.prototype.slice.call(arguments, 0);
          var max = getMax.apply(null, args);


          return args.reduce((sum, cur) => sum + cur * max * 10, 0) / 10 * max;
      }
      console.log(add(0.1, 0.2));