my window dvd OF 8.1 64BITS (P/N JDNFT Rev. A00)contain 26 digits of product key . how i can use this dvd actually nomally dvd consist of 25 digits product key?
DVD has product key is "US-0RGH4G-53590-59F-AG7V-REV-A00"  These are 26 digits ... whichnuber is extra in this key i don't know..

DELL5558 CORE I3

TAG :  [Admin NOTE: Service tag removed per TOU policy]

WINDOW 10 Already installed on my laptop