an emoticon that expresses extreme excitement above and beyond what any smilely face could convey. The symbol is a representation of the male genitalia in a state of full expression when viewed sideways.
The minimalist value of pi (unless you need a far better approximation to ensuring that someone lands safely on a distant planet, or that a computersystem is in good working conditions).
For most practical purposes involving the constant π, you’d do fine with the quick-and-dirty value of 3.