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# kryptos

In 1988, as a new headquarters for the American Central Intelligence Agency (CIA) was being built in Langley, Virgina, sculptor Jim Sanborn was commissioned to create artwork for the courtyard of the new building. In 1999, a computer scientist named Jim Gillogly announced that he had solved most of the puzzle. There were four distinct […]

# Pi is 4

A limit is something towards which you will always get closer and closer. This doesn’t mean you will eventually reach it. The euclidean length of a segment Δz=(Δx,Δy)Δz=(Δx,Δy) is Δx2+Δy2−−−−−−−−−√Δx2+Δy2 whereas the “taxicab” length of this segment is |Δx|+|Δy||Δx|+|Δy|. “In the limit” this implies that the euclidean circumference of the unit circle is 2π2π, whereas […]

# Latin square

The “Gamma plus two” method for generating “odd order” magic squares, the“Gamma plus two plus swap” method for generating “singly even order” magicsquares, and Durer’s method for generating “doubly even order” magic squares. By Professor Edward Brumgnach, P.E. City University of New YorkQueensborough Community College In combinatorics and in experimental design, a Latin square is […]

# N-Queens

Construct a magic square nxn (using the numbers 1 to n2) and place n queens only on these cells which contain prime numbers, such that no queen can take any other queen. 1. What is the smallest magic square (n) having solution? 2. Get one solution for the next three larger magic squares (n+1, n+2 […]

# Adventures in Group Theory

Adventures in Group Theory: Rubik’s Cube, Merlin’s Machine, and Other Mathematical Toys David Joyner 5-15-2008 Published on Jan 15, 2016 The vast majority of people who tackle the Rubik’s cube never succeed in solving it without looking up somebody else’s solution. In this video the Mathologer reveals a simple insight that will enable all those […]

# Lines

Construct nine triangles by drawing three straight lines through a capital M Starting with a pentagram, using only two additional straight lines, construct ten disjoint triangles You just bought TEN trees: Plant them in FIVE rows with FOUR trees in each row Advertisements

# pentomino

Pentominoes Pentominoes: Puzzles & Solutions PENTOMINOES – An Introduction A pentomino is a plane geometric figure formed by joining five equal squares edge to edge. It is a polyomino with five cells. There are twelve pentominoes, not counting rotations and reflections as distinct. They are used chiefly in recreational mathematics for puzzles and problems.[1] Pentominoes […]

# a handout given to physics students at Harvard

Common knowledge is a special kind of knowledge for a group of agents. There is common knowledge of p in a group of agents G when all the agents in G know p, they all know that they know p, they all know that they all know that they know p, and so on ad […]

# Einstein’s riddle

The situation There are 5 houses in five different colors. In each house lives a person with a different nationality. These five owners drink a certain type of beverage, smoke a certain brand of cigar and keep a certain pet. No owners have the same pet, smoke the same brand of cigar or drink the […]