It's the first day of the fourth grade at Arthimos Elementary and things are already off to a strange start--poisonous cookies, a zipline disaster, a missing iPad, and what are those strange sounds coming from the school custodian's wheelbarrow? Luckily the Prime Detectives--Abby "the Abacus" Feldstein, Cameron "Cam" McGill, and Gabriel "Gabe" Kim--are on the case! Using arithmetic, geometry, and logic, the Prime Detectives are sure to figure out who did what, when, and why! A gripping new middle grade mystery series, each book contains multiple, interlinked mysteries that readers help solve using math. Includes answers showing step-by-step solutions.