Changes

| accessdate = 2012-02-11}}</ref>, who selected  '''<big><math>\pi</math></big>''' because it is the first letter of the Greek word for [[perimeter]] (''περίμετρος''), i.e. the circumference of a circle is its perimeter.  A Swiss mathematician, [[Leonhard Euler]], brought the concept into general use in 1737.

| accessdate = 2012-02-11}}</ref>, who selected  '''<big><math>\pi</math></big>''' because it is the first letter of the Greek word for [[perimeter]] (''περίμετρος''), i.e. the circumference of a circle is its perimeter.  A Swiss mathematician, [[Leonhard Euler]], brought the concept into general use in 1737.

<big><math>\pi</math></big> is referenced in the [[Bible]], literature, and even as the title of a movie.  It is central to the most famous equation in all of mathematics:  [[Euler's Formula]].

<big><math>\pi</math></big> is referenced in the [[Bible]], literature, and even as the title of a movie.  It is central to the most famous identity in all of mathematics:  [[Euler's Formula|Euler's Identity]].

The value of '''<big><math>\pi</math></big>''' is approximately 3.1416, or 22/7. The exact value cannot be expressed as a [[fraction]] or as a [[decimal]] number, regardless of how many [[digit]]s are used. Johann Heinrich Lambert proved this in 1761 by showing that '''<big><math>\pi</math></big>''' is an [[irrational number]], which means that it can't be expressed as a fraction.<ref>{{cite web

The value of '''<big><math>\pi</math></big>''' is approximately 3.1416, or 22/7. The exact value cannot be expressed as a [[fraction]] or as a [[decimal]] number, regardless of how many [[digit]]s are used. Johann Heinrich Lambert proved this in 1761 by showing that '''<big><math>\pi</math></big>''' is an [[irrational number]], which means that it can't be expressed as a fraction.<ref>{{cite web