There are an estimated 1.618 million web sites dedicated to recreational mathematics. Many of them feature interesting and useful material, but there is mammoth duplication of content. I strongly desire not to contribute to the clutter, hoping to offer perspectives sufficiently unique that they will not be encountered elsewhere.
Doubtless these materials will interest only a small percentage of math nuts. No advanced learning is required here, however; a reasonable awareness of high-school math is sufficient.
A Challenge to Mathematicians:
Solve the "Black Box" Puzzle
A Special Continued Fraction for Square Roots
Pencil & Paper Square Roots Using Continued Fractions
Some Tips & Tricks for Mental Calculations
Be Your Own Perpetual Calendar — Calculate Dates in Your Head
The articles in this section are designed to be assimilated in numeric sequence. Each page features ideas or methods previously introduced.
1: Introduction to Programming a Four-Function Calculator
7: Extra Decimals for Square Roots
Black Box math challenge
Newton-Raphson
Babylonian Heron
square root iteration
Fibonacci
continued fraction
mental arithmetic
mathematics
pencil and paper
compound interest
logarithms
trigonometry
4-function calculator
Taylor series
arithmetic shortcuts
squared square