Có: \(A=2^2+2^3+...+2^{101}\)
\(A=2\left(2+2^2+...+2^{100}\right)⋮2\)
Lại có: \(A=2^2+2^3+...+2^{101}\)
\(A=\left(2^2+2^3\right)+\left(2^4+2^5\right)+...+\left(2^{100}+2^{101}\right)\)
\(A=3.2^2+3.2^4+...+3.2^{100}\)
\(A=3\left(2^2+2^4+...+2^{100}\right)⋮3\)