Hopscotch was originally a training exercise for Roman infantry. These frogs don’t know that history. They are just interested in jumping about on their lily…

Imagine that all living things are made up of joints and bones . For example, here are two flexi-fish swimming happily along: You can…

This problem is best for people who can express numbers in different bases. An abacus is a mechanical device for temporarily storing numbers during a…

The Egyptians only used fractions with a numerator of 1.* Take the fraction 80/100 and keep subtracting the largest possible Egyptian fraction till you get…

After an epic voyage across the Pacific, the Polynesian catamarans arrived on Rapa Nui (Easter Island) approximately 1500 years ago. The Island was a paradise…

Write the numbers 1 through 8 in the circles so that no two numbers inside circles joined by a line differ by 1. Here is…

Polyominoes are shapes that are made by gluing identical squares along their edges. A domino is a shape made from two squares glued along an…