{\bf 1.} Find out whether it is possible to express $1$ as a linear combination 
$1=m 11 +n 27$ for some integers $m$ and $n$,
and if it is, find them.

{\bf Ans.}: $m=$ \quad \quad \quad  $n=$ \quad \quad \quad 

{\bf 2.} Find $11^{16} \pmod 13$

{\bf Ans.}: