The Sky Serial Box Number from the Sky Menus is 10 digits all numbers
Not used a Sky Ireland card myself but cant see why there would be any issues. And yes HEX numbers are 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E & F so if it converts to a HEX number with an E at the end, then leave it as a E.
When converted to HEX it is 8 digits, so the last character can be an E, mine has a B in it
But if you mean the unconverted Decimal Box Number has an E, I would assume E = Eire, so ignore it and hopefully all will be well. Internet connection, not required.
empb