Abstract: Three modular arrays structured from a common module are connected together a first way to form a binary quotient by successive approximations, or a second way to form a binary product. Any one of the three modular arrays may be used to add or subtract two binary numbers. To divide, one array is utilized to effectively form the reciprocal of the binary divisor, most significant bit first, by successive approximation. Control circuitry, including a carry detector, dictates the formation of the shift and add sequence that effectively represents the reciprocal of the divisor by controlling the positioning of the divisor before each addition step so that the product is a series of binary ones. The add and shift sequence utilized to generate the series of binary ones, as it is evolving, is also being utilized to manipulate the dividend, thereby forming the quotient, most significant bit first.