An information processing system that is configured in such a manner that computational processing is performed on input data in accordance with a processing sequence, for outputting data, comprises: a plurality of arithmetic units (7-1 to 7-x), each computing at an arithmetic precision 2.sup.m bits (where m is a natural number) based on the processing sequence; and a plurality of cascade connection terminals for cascading these arithmetic units each other. When the maximum arithmetic precision that is required during computational processing is 2.sup.n bits (where n is a natural number and is fixed), x numbers of (where x is a natural number) the arithmetic units are cascaded in a manner such that the inequality x.gtoreq.2.sup.n/2.sup.m is satisfied. When an arithmetic precision of 2.sup.n1 bits (where n1.ltoreq.n, and n1 is variable) is necessary during computational processing, x1 numbers of the arithmetic units are cascaded in a manner such that the inequality x1.gtoreq.2.sup.n1/2.sup.m (where x1 is a natural number and is variable) is satisfied. This makes it possible to easily implement an information processing system for performing computations to any desired precision in a hardware manner, and also makes it possible to support a simple hardware-based method of expanding the arithmetic precision.