Pi ( ) is a universal constant indicate the ratio of circumference of a circle and its diameter. The value of has been estimated since Archimedes (see: Phillips, 2000 ).
Using MS excel, we can use function =PI() to represent
Example
Accuracy 
Pi as ratio 
Error (computed from PI of MS Excel) 
0.1 


0.001 


0.00001 


0.0000001 


Now you can
download the Spreadsheet companion of this tutorial
and try PI() for different accuracy
This tutorial is copyrighted .
Preferable reference for this tutorial is
Teknomo, Kardi (2015) Continued Fraction. http://people.revoledu.com/kardi/tutorial/ContinuedFraction/index.html