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.

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.

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

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

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.

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

King Arthur was a good ruler, but in this math adventure he needs a good ruler. Geometry is explained with humor in SIR CUMFERENCE AND THE FIRST ROUND TABLE, making it fun and accessible for beginners. What would you do if the neighboring kingdom were threatening war? Naturally, you'd call your strongest and bravest knights together to come up with a solution. But when your conference table causes more problems than the threat of your enemy, you need expert help. Enter Sir Cumference, his wife Lady Di of Ameter, and their son Radius. With the help of the carpenter, Geo of Metry, this sharp-minded team designs the perfect table conducive to discussing the perfect peace plan. Thanks to Sir Cumference, even the most hesitant will be romancing math.

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.

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.

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?