You have not specified the purpose for which Book value is required.
prima facie, the following are the methods :-
Method 1 - Straight forward method :-
NAV = A / B
Where A means
Share Capital + Reserves & surplus + Other share holders funds - Accumulated losses - Prel/deferred reveune expenses
B means = No of shares of the Company.
Method 2 :- Discounted future cash flows method
You need to arrive at the future cash flows for the company for the next X years and discount the same to current value by applying Discount factor and arriving at the value
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