Cut The Knot

An Interesting Number: a story concerning 1729, Hardy-Ramanujan conversation and R. Feynman

a proof that the GCD of two Fibonacci Numbers is the number that corresponds to the gcd of their indices

Sightings of Pi in Pascal

12 Coins in Verse: A verse to remember a solution to the 12 coins puzzle

The area of a parallelogram defined by two vectors is easily expressed by a 2x2 determinant. John Molokach noticed that the formula leads to a proof of the Pythagorean theorem

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Math Lingo vs. Plain English. An article from the American Math Monthly

considering special cases is a stepping stone in understanding the problem; seeking an analogous or related problem; splitting the problem into smaller ones