Add Comma to Sequential Numbering

I admit that I am not a programmer, but I have been using Fusion Pro for about a year. Mostly for sequential numbering. For the first time I have a need to add a comma to my numbers. Here is the rule that I am currently using for numbering. Can it be modified to add a comma? Help! Thanks!

var start = "10001";

var LeadingZero = "00000";

new_val = start-1

return '<z newsize="50"><setwidth newsize="25">' + FormatNumber(LeadingZero, new_val + CurrentRecordNumber());

Thanks!!!

Change this line:

var LeadingZero = "00000";

to:

var LeadingZero = "00,000";