Sorry I am a bit lost here with your calculations whilst evaluating the company.
You say
1) market cap of Sical is 900 cr so 50% is 450 cr. 1/6 of 450 is indeed 75 cr (as you suggest) so the value of the holding should be 5/6 (discount = less by 1/6) which is 375 cr.
2) Similarly for the Mindtree valuation. 16.6% of 10,500 cr is 1743 cr of which 5/6 is 1452.
Both together contribute 375 + 1452 = 1828 approx. Add cash of 197 = 2025 so you get the other parts of the company for 6756 - 1828 = 4732 cr. Then add 2100 cr for debt EV = 6832cr (as opposed to your calculation of 7900 cr).
The difference in calculations is that you discount the value of the holdings of Sical and Mindtree to 1/6 whereas I discount by 1/6.
Maybe I am doing something wrong. Please advise.
Nevertheless, the story does not look good to me with the political angle and capital allocation.
BTW, apart from Rakesh Jhunjhunwala I believe his mentor Radha Kishen Damani is also an investor through his Derive investments. But why go by them. RJ also invested in A2Z maintenance and Bilcare.
Regards
Kumar