Do evolution take many generations to occur?

All else being equal, the more generations you have the more quickly evolution happens. Usually only laboratory scientists studying quickly reproducing life forms, like single celled creatures and some invertebrates, have the opportunity to see evolutionary change happen before their eyes .

a "theory" a suggestion that is not 100 % accurate, or a figure. some people say its a theory because they of all the passed theory's about one subject. it depends sometimes theory might be accurate and sometimes they are.

this is math not biology xd