\(M=1+3+\left(3^2+3^3+3^4\right)+\left(3^5+3^6+3^7\right)+...+\left(3^{98}+3^{99}+3^{100}\right)\)
\(M=4+13\cdot\left(3^2+3^5+...+3^{98}\right)\)chia 13 dư 4
\(M=1+\left(3+3^2+3^3+3^4\right)+...+\left(3^{97}+3^{98}+3^{99}+3^{100}\right)\)
\(M=1+40\cdot\left(3+...+3^{97}\right)\)chia 40 dư 1