- Square of the Difference of two numbers is their Sum
- Difference of the Squares of two numbers is their Sum
- Order-3 Magic Squares
- Triangle Numbers
- Square Triangles
- Reversible Factors and Multiples
- Liar's Paradox
- Pythagorean Triples
- Sum of Two Numbers is a Multiple of their Difference
- How the Quadratic Formula is Derived