An Unsolved Proof

Hidden cameras, secret operations, and new math concepts await in the Math Kids' ninth adventure!

Justin has been accused of stealing from the comic book shop! To earn back the trust of his parents and the store manager, he'll have to work at the shop for four whole weekends. And that puts a damper on his plans to play video games and hang out with fellow Math Kids, Jordan, Catherine, and Stephanie.

With the end of summer approaching, the four friends realize that finding proof of Justin's i...