document.write(Number.MIN_VALUE + "<br/>");  //5e-324
 document.write(Number.MAX_VALUE + "<br/>");  //1.7976931348623157e+308
 document.write(Number.NaN + "<br/>");   //NaN
 document.write(Number.NEGATIVE_INFINITY + "<br/>"); //-Infinity
 document.write(Number.POSITIVE_INFINITY + "<br/>"); //Infinity

 var num = Number(5.123);      //5.123
 document.write(num.toString() + "<br/>");  //5.123
 document.write(num.toFixed(2) + "<br/>");  //5.123
 document.write(num.toPrecision(2) + "<br/>"); //5.123
 document.write(num.valueOf() + "<br/>");  //5.123
 document.write(num.toExponential(1));   //5.1e+0