If you have never used books by Greg Tang, let me introduce you! This is one that my students always enjoy.
This is one of the books that I usually save for the end of the year. After state testing in April we focus on "Get Ready for Fourth Grade" lessons in math. I love to pull out this book and do just one or two riddles per day.
This book challenges students to think about the math problems using patterns, groupings, and other ways. Check out the video.
You also need to explore the Greg Tang website! Click on the Books tab and then this book for an online activity to go with the book.