Dear sir, I have 465.5 marks in 10th but in cat form there are not any entry after decimal, what can I write?

Dear Rahul, CAT Interface allows you to enter marks in nnn.nn format. After typing in the first 3 digits, if you place a decimal and try to enter the remaining digits, it will not allow you. To avoid the mistake, do not enter the decimal. Rather try typing 46550. The interface will automatically capture the decimal.

Just write 465 marks that'll enough
The Common Admission Test is a computer based test for admission in a graduate management program. The test scores a candidate on the bases of Quantitative Ability, Verbal Ability and Reading Comprehension, Data Interpretation and Logical Reasoning. A candidate is eligible to appear in CAT 2019 if he/she holds a Bachelor's Degree with at least 50% marks or equivalent CGPA. The candidates belonging to Scheduled Caste (SC), Scheduled Tribe (ST) and Differently Abled (DA) categories, need at least 45% marks

Feel free to comment if you have any doubt
Good luck