Here's how return of premium plans work
Let's say basic premium is ₹100 per year and policy term is 10 years. The insurer expects a return of 6% on their money. So how much do you need to put to have ₹1000 at the end of 10 years? Put this in Excel
=PMT(0.06,10,0,1000)
The answer is 75.87
So...