This video shows how PI is calculated by using the Pythagorean Theorem in an algorithm that calculates the hypotenuse of an increasing number of triangles within the circle - akin to pizza slices in a pizza pie. An overview of the algorithm is given, followed by the actual formulas being implemented in excel.
The output after 24 iterations of the main algorithm calculates Pi to 15 decimal places - the limit of Excel's calculating engine. The result is compared against the Excel formula for Pi which is "=PI() " and shown to be identical. At this point, the formula calculates the length of the hypotenuse of over 67 million triangle slices in order to determine the value of Pi out to 15 decimal places.
Further iterations of the algorithm calculate the lengths of an increasing number of hypotenuse that would result in a more refined value for Pi, were it not for the limitation of Excel.