Pi is the ratio between the circumference and diameter of a circle. It is an irrational number approximately equal to 3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117067.
Yes. I have worked in a phone bank (a room full of people all making phone calls to potential donors) for a charity at least a dozen times and volunteered to serve food in a soup kitchen five or six times.