docs: function(num) {
              if(typeof num !== "number") {
                  return NaN;
              }
              var isNegative = num < 0;
              num = (isNegative) ? -num : num;
              var log = this.logBaseTen(num),
                  result = Math.pow(10, Math.floor(log));
  
              return (isNegative) ? -result: result;
          }