@yatinjhamb Well, that isn't really an Excel problem, is it? Unless I misunderstand, of course.
When you have 300000 forms that take 3.5 minutes each to check you need 1 million and 50 thousand minutes in total to complete the task. That would be 17500 hours, or roughly 2200 working days or roughly 100 working months. Hire 100 people and your done in a month. Do it all by yourself, and it will take you 8 years.