Net worth deemed cost for slump sale; fair market value treated as full consideration; unpurchased goodwill treated nil. For slump sale transfers, the net worth of the undertaking or division is deemed to be the cost of acquisition and improvement for capital gains computation, with the second proviso to section 48 disregarded; the fair market value of capital assets on the date of transfer is deemed to be the full value of consideration, and goodwill not acquired by purchase has nil cost.