Mumbai, May 6 -- Billionaire banker Uday Kotak and his family have made the country's most expensive real estate purchase, buying a flat in the 19 Shiv Sagar building at Worli Sea Face at Rs.2,74,784 per square foot. According to property portal IndexTap, the Kotaks recently bought 10 apartments of varying sizes in the building for Rs.224.32 crore. The Kotaks now own 22 of the 24 apartments in the ground-plus-two-storey building, for which they have paid Rs.426.21 crore in total. P5...