$M = 2^{2020} - ( 2^{2009} + 2^{2008}+ ... + 2^1+ 2^0)$
Đặt $A =2^{2009} + 2^{2008}+ ... + 2^1+ 2^0$
$A = 2^0 + 2^1 +...+ 2^{2008} + 2^{2009}$
$2A = 2^1+ 2^2+... + 2^{2009} + 2^{2010}$
$2A - A = (2^1+ 2^2+... + 2^{2009} + 2^{2010}) - (2^0 + 2^1 +...+ 2^{2008} + 2^{2009})$
$A = 2^{2010} - 1$
$= >$ $M = 2^{2020} - A = 2^{2020} - 2^{2010} - 1$