# Math Fair Category: Number Concepts

## Froggy Hopscotch

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…

## Flexi Fish

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

## Factorial Abacus

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…

## Egyptian Fractions

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…

## Easter Island

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…

## Digit Placing Puzzle

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…

## Counting Polyominoes

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…