Math Man might be a barrel of fun, but he’s not going to be teaching readers much math. Marnie’s class is off to Mighty Mart to see a little math in action. Garth, a.k.a. Math Man, is a clerk with a talent for math. (A contemporary fantasy, obviously.) He races about the store, advising shoppers on their purchases: get a quarter of a watermelon, it fits in the fridge better; or to a mother—“There are four Dinkies in that box, ma’am. And you’ve got five kids. How about a family pack of ten . . . two snacks each?” By the end of the story, when the cash registers have gone on the blink and Math Man is adding colossal columns of figures in his head, readers will swoon at his command of all those numbers. Problem is, readers will not be able to do the same, nor do they get any inkling of the mechanics behind the math—a troop of mice play a cameo role by introducing equations into the marginalia, but without an explanation, the equations’ rationale goes begging. Math Man’s value and appeal lies in his enthusiasm, which Bush (*Ferocious Girls, Steamroller Boys, and Other Poems in Between*, 2000, etc.) conveys through exuberant, cornball illustrations full of mousy fun, but the best that can be hoped for here is a provocation to learn the meat of the math elsewhere. *(Picture book. 6-8)*