Can This Definition of Pi Work in More Abstract Algebras?

Gerenuk
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I quite like the following definition of pi and I wonder which minimal algebraic rules are needed to make this definition work?

\lim_{n\to\infty}\left(1+\frac{a}{n}\right)^n=1
\therefore |a|=2\pi k

(For example, are there algebras more general than complex numbers, where this works?)
 
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Well, in the quaternions e^{2\pi u} = 1 where u is any quaternion with u^2 = -1
 
So quaternions probably also work.

Any more abstract algebra? Hmm, what do I need? I need addition, multiplication, scalar division, limiting process and modulus, right? What has to be fulfilled as to yield pi then?
 
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