i tend to forget the things very much. should i revise? do others have this problem too?

Hi Sameer !!

You should know that you're not the only one who has this problem.

Almost all the IIT JEE aspirants face this problem of forgetitng concepts. So, keep revising your concepts on a weekly basis. In case you are in class 12th, Working on the questions from Sample papers would be really helpful. Because they cover all the topics of the three subjects.

All the Best !