Fix typos

Advanced/Generating Functions/parts/02 dice.tex

@@ -79,7 +79,7 @@ Using generating functions, find two six-sided dice whose sum has the same
 distribution as the sum of two standard six-sided dice? \par
 
 That is, for any integer $k$, the number if ways that the sum of the two
-nonstandard dice rolls as $k$ is equal to the numer of ways the sum of
+nonstandard dice rolls as $k$ is equal to the number of ways the sum of
 two standard dice rolls as $k$.
 \hint{factor polynomials.}
 \begin{solution}