Hello aspirant,
If you forgot to write the question booklet series during an examination, it's important to take the necessary steps to address the situation. Here are some suggestions:

1. Visit the Examination Office: After the exam, if you realize the mistake, consider visiting the examination office or contacting the relevant authorities at your educational institution. Explain the situation and provide any additional information they may need to identify your answer sheet.

2. Contact Examination Helpline or Support: Many educational institutions have helplines or support services for exam-related queries. Reach out to them and explain the issue. They may guide you on the appropriate steps to take.

3. Write a Letter of Explanation: If necessary, you may be asked to write a letter of explanation to the examination authorities, clarifying the oversight and providing any relevant details to help identify your paper.

Thank you