Dear Aspirant,

Do not worry about the same. While filling up the form initially, the Olympiad association might have inquired for your contact details, wherein you might have submitted your email & contact details. Kindly check your email box if you can find the registration number there. Also look at your messaging application wherein you may find the registration number.

If this doesn't help you, kindly contact the Olympiad Authorities via email/call & try to retrieve your registration number.

Thanks, hope it helps.