[freebeard]

First, they define the "gradian" as 1/100th of a quarter circle, thus making it inevitiable to use powers of 2 for half and full circles, while the very common 30 and 60 degree angles become infinitely-repeating decimals.

What could possibly go wrong!

Tau

https://en.wikipedia.org/wiki/Pi#In_popular_culture

In 1958 Albert Eagle proposed replacing π by τ = π/2 to simplify formulas. However, no other authors are known to use τ in this way. Some people use a different value, τ = 6.283185... = 2π, arguing that τ, as the number of radians in one turn or as the ratio of a circle's circumference to its radius rather than its diameter, is more natural than π and simplifies many formulas... However this use of τ has not made its way into mainstream mathematics.