Possible Duplicate:
Groups of real numbers
A group as we all know is a set A with a binary operation "" defined on it such that for every a,b belongs to A ab belongs to A, the operation is assocaitive, there exists an identity element and for every a in A there exists a unique p in A such that a*p=identity element. Can anyone provide me examples of groups where the operation defined on the set is not addition + or multiplication x.