[tex]2\equiv2\mod7[/tex]
[tex]2^2\equiv4\mod7[/tex]
[tex]2^3\equiv8\equiv1\mod7[/tex]
[tex]91=3(30)+1[/tex]
[tex]\implies2^{91}\equiv(2^3)^{30}\times2^1\equiv1^{30}\times2\equiv2\mod7[/tex]
[tex]6\equiv-1\mod7[/tex]
[tex]6^2=6\times6\equiv6(-1)\equiv-6\equiv1\mod7[/tex]
[tex]27=2(13)+1[/tex]
[tex]\implies6^{27}\equiv(6^2)^{13}\times6^1\equiv1^{13}\times6\equiv6\mod7[/tex]
[tex]\implies2^{91}\times6^{27}\equiv2\times6\equiv12\equiv5\mod7[/tex]
