if you break up each digit of any given number, there is no…

if you break up each digit of any given number, there is no way to create a number larger than that number from any combination of the product operator

99
9*9 = 81

999
9*9*9 = 721
9*99 = 891

9999
9*9*9*9 = 6561
99*9*9 = 8019
999*9 = 8991