9 Cupcakes!

Today, my sister decided to bake some cakes. Once they were out the oven, she put them on the table for them to cool down before she iced them. I came down the stairs to find Millie standing by the table licking her lips. There were 2 rows of cakes, and one row was a cake shorter than the other. I guessed Millie must have eaten the cake, but k wasn't going to accuse her of it because I didn't know for sure. A few minutes later my sister came in and started asking who had eaten the cakes! It turns out that there were actually 3 rows of cakes, each row the same length! Millie had only gone and eaten 9 cakes - and the wrappers!