Why you might need a friend.

• A = B * 2.75;

• translates to

• A = B.operator*(2.75);

• B can be of type Time.

• But, A = 2.75 * B;

• 2.75 cannot be type Time!!

• Most operators can be overloaded by member functions or non-member functions. Therefore compiler could match with A = operator*(2.75, B);

• prototype: Time operator*(double m, const Time & t);