Speculation that Hong Kong actor and television personality Johnny Tang Siu-chuen earned HK$1.7 billion from interest on a rumored HK$1.5 billion inheritance is mathematically improbable, according to simple calculations based on bank interest rates.
Online articles recently hailed Tang, son of late Cantonese opera star Sun Ma Si-tsang, as a highly successful "second-generation rich" for supposedly turning his inheritance into more than its original value over 27 years by just depositing it in a bank.
However, this timeline is flawed. Tang's high-profile legal dispute over his father's estate ended only in 2006, meaning the funds would have been in a bank for a maximum of 20 years, not 27.
Using the rumored principal of HK$1.5 billion and an estimated average annual interest rate of 2.2 to 2.5 percent, the total simple interest earned over 20 years would be approximately HK$666 million. This would provide an average passive income of about HK$2.4 million per month.
Even with compound interest, the total would only reach around HK$827 million—far short of the claimed HK$1.7 billion. While a monthly income covering reported expenses of HK$500,000 for his three partners is plausible, the viral claim of earning more than the principal from interest alone does not hold up.
