The Triangle Secret : Common Deer Press : 9781988761626 : 198876162X : 01 Apr 2022 : A Mysterious Will Launches The Math Kids Into Their Riskiest Adventure Yet! When FBI Special Agent Carlson is kidnapped while investigating the plane crash of Willard Howell, an eccentric billionaire inventor, the Math Kids spring into action. If Catherine, Stephanie, Justin, and Jordan can figure out the Great Triangle mentioned in Howell's will, they might just uncover who's behind the crash and Agent Carlson's kidnapping-if they don't get caught themselves! This Middle Grade Book - introduces readers to mathematical patterns - features an action-packed plot with international intrigue - includes an appendix for hand-on learning