Bye to pi

Mathematicians want "tau" instead of "pi".  

Measure the longest distance around a circle and divide it by the shortest distance across and you get the ratio called pi.  That shortest distance is the diameter.  Most math about round things uses "r" for radius instead of "d" for diameter because radius is the simplest way to generate a circle.    Using the more logical "r" for the calculation,  the value called pi will have to double to keep the equations right.  That new number would be Tau.
Old:   π      =  3.141593 etc  (Pi to a million places)  (22 ÷ 7  usually good enough.)
New:  τ       =  6.283185 etc

Suggested by Brian Hall