Answer
The digit symbol for base 9 is 0 to 8.
P is preceding numberof \[{{888}_{nine}}\].
\[\begin{align}
& P={{888}_{nine}}-1 \\
& ={{887}_{nine}}
\end{align}\]
F is following numberof \[{{888}_{nine}}\]. The digit symbol for base 9 is 0 to 8.
\[F={{888}_{nine}}+1\]
In base nine, \[{{8}_{\operatorname{nine}}}+1={{10}_{nine}}\]
\[F={{1000}_{nine}}\]