\begin{definition}[Definition:Reversal]
Let $m = \sqbrk {a_n a_{n - 1} a_{n - 2} \ldots a_2 a_1 a_0}$ be an integer expressed in base $10$.
That is:
:$m = \ds \sum_{k \mathop = 0}^n a_k 10^k$
Its '''reversal''' $m'$ is the integer created by writing the digits of $m$ in the opposite order:
:$m' = \sqbrk {a_0 a_1 a_2 \ldots a_{n - 2} a_{n - 1} a_n}$
That is:
:$m' = \ds \sum_{k \mathop = 0}^n a_{n - k} 10^k$
\end{definition}