When Marnie's class visits the Mighty Mart, they find that the store is hopping with vexing math problems. Fortunately, Math Man (also known as Garth, the stock boy) has plenty of solutions. No room for a whole watermelon in your fridge? Try quarter slices. Can't feed five children with four snack cakes? Buy the easy-to-divide family ten pack.

But Math Man's skills are really put to the test when all the cash registers go kaput. Thank heavens he can add the contents of sixty baskets in his head!