Likable, clever, and inventive sixth-graders Rufus Mayflower and Kate Mackinstrey develop and sell toothpaste to become millionaires in just one year! This fun, breezy story includes many real-life mathematical problems which the characters must solve to succeed in their budding business.

Jean Merrill is the award-winning author of over thirty books for children, including The Superlative Horse, The Black Sheep, and the wellknown satirical novel The Pushcart War.