Yes, you’re right. Sum-of-part is applicable for conglomerate and it is being used for companies that own multiple business in different industry. Basically, it is using all the valuation method (P/E, P/B, DCF, etc) you’ve learned and value each division of the conglomerate respectively. And finally, you add them all together and that’s the estimate value of the company.
Boustead, for example, owns four divisions; geospatial, oil & gas, property and waste water mgt. Take one example, we can value the oil and gas individually and since it is a cyclical company, I would estimate a low multiple to earnings, i.e. say 5 times of average earnings for past five years. Then we can repeat the valuation for other divisions using appropriate valuation method.
Do want to try the rest of the valuation? Remember, valuation is form of art and there is no right or wrong to it. The challenge with it is getting the right balance and not overly conservative or aggressive.