A showdown between two barbers in the frontier town of Cowlick leads them to realize new uses for scale drawing.

When young Per visits her uncle Sir Cumference and his family, she learns how to play the game, "Inners and Edges." After she finds a clue linking the game to the mysterious castle on the island of Immeter, she must figure out how to find the perimeter and area of a circle to unlock the island's secret.
Math skills taught include finding the area and perimeter of a rectangle and a circle. Introduces an underlying concept of calculus -- using straight lines to measure curves.

A ribbiting math adventure
After being banished to the Abyss of Zero in MULTIPLYING MENACE: THE REVENGE OF RUMPELSTILTSKIN, Rumpelstiltskin is back, and he's stirring up more trouble than ever. Together with his sidekick, a witch named Matilda, Rumpelstiltskin plots his revenge on Peter and uses his magical powers to divide the kingdom into frogs. Peter and his dog, Zero, must locate the Great Multiplier and find a solution that will break the Great Divide before Rumpelstiltskin has a chance to combine the two mighty math sticks. Can Peter once again save the kingdom in time, or will it meet a green and warty fate?
Young readers will fall in love with this math adventure and learn all about dividing by whole numbers and fractions, as well as division rules for equations involving zero. Beautifully rendered illustrations will grab readers' attention as they learn basic math skills in a fun and inventive way. Back matter includes a summary of the basics of division.

Sir Cumference, Radius, and Sir Vertex search for Edgecalibur, the sword that King Arthur has hidden in a geometric solid.

Radius is on a quest to earn his knighthood! With only a circular medallion, a mysterious poem, and his own wits to guide him, he must find and rescue a missing king. Includes plastic protractor

When Sir Cumference drinks a potion which turns him into a dragon, his son Radius searches for the magic number known as pi which will restore him to his former shape.

A clever introduction to place value.
Sir Cumference and Lady Di planned a surprise birthday party for King Arthur, but they didn't expect so many guests to show up. How many lunches will they need? And with more guests arriving by the minute, what about dinner? Sir Cumference and Lady Di have to figure out a quick way to count the guests to bring order to the party.
Sir Cumference and his friends have been entertaining young and old alike for years as they introduce important math concepts with clarity and humor.

The eighth book in the popular Sir Cumference series, SIR CUMFERENCE AND THE OFF-THE-CHARTS DESSERT introduces readers to different methods of collecting data.
Sir Cumference and Lady Di of Ameter are in a pickle. The castle cook is sick and the Harvest Faire is coming up--who will make the special dessert for this annual event? Two bakers in town, Pia of Chartres and Bart Graf, are up to the task. But after sampling Pia's delicious pies and Bart's scrumptious cookies, Sir Cumference and Lady Di just can't choose They come up with a solution: hold a contest and let the townspeople choose the dessert to be served at the faire.
When Pia and Bart's methods of tracking their votes fail, they each realize they need to come up with a better system. Pia places a colored candy around the edges of a pie dough and Bart stacks his cookie molds--each color candy or mold shape represents a different kind of pie or cookie. Thus, the pie chart and bar graph are born But when the contest ends in a tie, Pia and Bart concoct a hybrid recipe that everyone enjoys.

Assisted by his knight, Sir Cumference, and using ideas offered by his wife and son, King Arthur finds the perfect shape for his table.

While riding through the forests of Angleland, cousins Per and Radius realize they are lost and are desperate for a map to guide them home. Soon they come across a mysterious house in the hills. Inside they find a map to a treasure belonging to Xaxon Yellowbearyd, the fiercest Viking warrior of his time. Per and Radius must decode the strange numbered grid on the map, while trying to steer clear of the pack of bungling bandits who are on their tail. Will they find the treasure in time?

Rumpelstiltskin is back! This time he's making mischief with his multiplying stick. Can Peter unlock the secret of the stick in time to save the kingdom? Whimsical illustrations bring fun to multiplying whole numbers and fractions.