Last 5 digit of ISBN

Hi,

I need to catch the last 5 digit numbers from the 13 digit ISBN, if it possible to capture with the script?

Example: 9840000123412

var myNumber = 9840000123412;

alert(myNumber)

var mySplit = myNumber.replace(/\d{5}/, "") //here i get a problem

alert(mySplit)

Output need this: 23412

Thanks,

V.