- In the fifth book of the series your kiddo will meet a new friend, Silla Willa Aunt Fourilla, Monkey Moe’s aunt who really, really, really LOVES vanilla! Not Dan knows that skip counting by fours isn’t as easy as twos. The numbers start increasing and this is when kiddos tend to get scared by math, and building “the WALL”. Willa will help your kiddo look at these “big numbers” as just her age on that birthday. Also, thanks to Monkey Moe, they will be too focused on the surprises that Willa has in store for her on her way to the big “Four-0″! Enjoy!