Aztec Calendar

Wiki Wednesday – Doomsday Rule

The Doomsday rule or Doomsday algorithm is a way of calculating the day of the week of a given date. It provides a perpetual calendar since the Gregorian calendar moves in cycles of 400 years. This algorithm for mental calculation was devised by John Conway after drawing inspiration from Lewis Carroll’s work on a perpetual…


Wiki Wednesday – Ulam Spiral

The Ulam spiral, or prime spiral (in other languages also called the Ulam Cloth) is a simple method of visualizing the prime numbers that reveals the apparent tendency of certain quadratic polynomials to generate unusually large numbers of primes. It was discovered by the mathematician Stanislaw Ulam in 1963, while he was doodling during the…