The Grapes Of Math by Greg Tang
Ages 9-12. 40 pages. A book of math riddles set in rhyming verse that encourages the use of problem solving strategies.
Math Curse by Jon Scieszka
Ages 5-10. 32 pages. A silly story where a child is "afflicted" by seeing everything in life like a math problem.
The Phantom Tollbooth by Norton Juster
Ages 8 and up. 256 pages. A young boy who doesn't see the purpose of anything sets off an a fantasy adventure to save the princess, Rhyme and Reason.
Only One by Marc Harshman
Ages 6 and up. 32 pages. For kids who have mastered 1-1 correspondence, this books extends the concept of sets by examining groups you find at a county fair.
Stories with Holes
Ages 4-8. Approximately 20 pages. Each of the 15 books in this series offers you around 10 story puzzles to work out. You get a very basic and seemingly impossible story or mini-mystery to figure out. You ask an unlimited number of yes/no questions until you figure out how the story came to be.