Abstract: Apparatus including a calculator that can also function as a horn button is provided for a motor vehicle. The apparatus is mounted on the center of the steering wheel and its downward depression actuates the horn circuit of the vehicle in the same manner as does a conventional horn button. At other times, the keys associated with the calculator portion of the provided apparatus may be operated to perform whatever calculations the operator may desire during periods of time in which the operator's attention is not required for the operation of the motor vehicle.