Book value vs market value when selling shares in multi-family

[Corey Good]

I'm invested in a few commercial and multi-family projects and am looking into exiting the partnership. In our operating agreement, in the first 4 years, you can request out at a fair book value. In year 5, you can request out at fair market value. I'm trying to understand how much of a difference that would make in exiting the deal and how I could evaluate and calculate how much that would be. Any value would be appreciated!