The letter contains many helpful insights and very thorough analysis of BRK. But anyone else has issue with the way he proves that high growth of Fab 5 is "mathematically impossible" as shown by the tables on P63 and P64? We can discuss/debate all day about many fundamental reasons why Fab 5 will or will not grow at high rates for the next decade or two, but high growth of any company will not mathematically impossible. I believe the set up of the tables were mathematically wrong, as you need to account for the growth of Fab 5 in the first grow of the table, i.e. you can not assume S&P as a whole will only grow 4% when Fab 5 (part of S&P) grow, say 20%, for two decades. The right way is to calculate the first row in the table by assuming all companies other than Fab 5 grow 4% and Fab 5 grow at whatever rates you assume.