examinee's number; candidate number
The identification number assigned to an examinee, used on admission tickets, answer sheets, and result announcements.
Your examinee number is written on the admission ticket.
Please look for your candidate number on the pass list.
受験票 is the admission ticket itself, while 受験番号 is the number printed on it.
Compound of 受験 (taking an examination) and 番号 (number).