  Throughout more than two millennia many formulas have been obtained, some of
them beautiful, to calculate the number pi. Among them, we can find series,
infinite products, expansions as continued fractions and expansions using
radicals. Some expressions which are (amazingly) related to pi have been
evaluated. In addition, a continual battle has been waged just to break the
records computing digits of this number; records have been set using rapidly
converging series, ultra fast algorithms and really surprising ones,
calculating isolated digits. The development of powerful computers has played a
fundamental role in these achievements of calculus.
