15. (6 points) A little squirrel stored some pine cones for the winter. The little squirrel originally planned to eat 6 pine cones per day, but actually ate 2 more than planned each day, and as a result, finished the pine cones 5 days earlier. How many pine cones did the little squirrel store in total?
120
【Solution】Solution: $(6+2) \times[(5 \times 6) \div 2]$
$$
\begin{array}{l}
=8 \times 15, \\
=120 \text { (pieces). }
\end{array}
$$

Answer: The little squirrel has stored a total of 120 pine cones.
So the answer is: 120.