Pi number : There are the infinities of the everyday, as exemplified by the figure of pi ( π ), with its endless post-decimal tail of nonrepeating digits, and how about if we just round it off to 3.14159 and then serve pie on March 14 at 1:59 p.m.? Another stalwart of infinity shows up in the mathematics that gave us modernity: calculus.
“All the key concepts of calculus build on infinite processes of one form or another that take limits out to infinity,” said Steven Strogatz, author of the recent book “The Joy of x: A Guided Tour of Math, From One to Infinity” and a professor of applied mathematics at Cornell. In calculus, he added, “infinity is your friend.”
The ratio of a circle’s circumference to its diameter is always the same: 3.14159… and on and on (literally!) forever. This irrational number, pi, has an infinite number of digits, so we’ll never figure out its exact value no matter how close we seem to get. Reynaldo Lopes explains pi’s vast applications to the study of music, financial models, and even the density of the universe.
watch this video carefully