π (or pi) is a mathematical constant that is the ratio of a circle's circumference to its diameter. It is approximately equal to 3.14159. π is an irrational number, which means that it cannot be expressed exactly as a ratio of two integers, although it is roughly approximated by 22/7. It is a transcendental number – a number that cannot be produced with a finite sequence of algebraic operations (sums, products, powers, and roots). The transcendence of π implies that it is impossible to solve the ancient challenge of squaring the circle with a compass and ruler. The digits in the decimal representation of π appear to be random. Because its definition relates to the circle, π is found in many formulae in trigonometry and geometry, such as Euler's identity, eiπ + 1 = 0. It is also found in formulae from other branches of science, such as cosmology, number theory, statistics, fractals, thermodynamics, mechanics, and electromagnetism.

Read more: https://en.wikipedia.org/wiki/Pi

_______________________________ Today's selected anniversaries:

1793:

Two days after becoming the first recorded European to complete a transcontinental crossing of North America north of Mexico, Scottish- Canadian explorer Alexander Mackenzie reached the westernmost point of his journey and inscribed his name on a rock. https://en.wikipedia.org/wiki/Alexander_Mackenzie_(explorer)

1802:

Gia Long conquered Hanoi and unified modern-day Vietnam, which had experienced centuries of feudal warfare. https://en.wikipedia.org/wiki/Gia_Long

1934:

Bank robber John Dillinger (pictured), whose exploits were sensationalized across the United States, was shot dead by police in an ambush outside the Biograph Theater in Chicago. https://en.wikipedia.org/wiki/John_Dillinger

1991:

American serial killer Jeffrey Dahmer was arrested in Milwaukee, Wisconsin, after police discovered human remains in his apartment. https://en.wikipedia.org/wiki/Jeffrey_Dahmer

2002:

The Israeli Defense Forces dropped a bomb on the home of Salah Shehade, the leader of the military arm of Hamas, killing him and his family. https://en.wikipedia.org/wiki/Salah_Shehade

_____________________________ Wiktionary's word of the day:

roundelay: (music) A poem or song having a line or phrase repeated at regular intervals. https://en.wiktionary.org/wiki/roundelay

___________________________ Wikiquote quote of the day:

It is better the truth should come little by little. I have learned that, being a priest. Perhaps, in the old days, they ate knowledge too fast. Nevertheless, we make a beginning. It is not for the metal alone we go to the Dead Places now — there are the books and the writings. They are hard to learn. And the magic tools are broken — but we can look at them and wonder. At least, we make a beginning. And, when I am chief priest we shall go beyond the great river. We shall go to the Place of the Gods — the place newyork — not one man but a company. We shall look for the images of the gods and find the god ASHING and the others — the gods Lincoln and Biltmore and Moses. But they were men who built the city, not gods or demons. They were men. I remember the dead man's face. They were men who were here before us. We must build again. --Stephen Vincent Benét https://en.wikiquote.org/wiki/Stephen_Vincent_Ben%C3%A9t