Modern processors incorporate complex arithmetic units that can work with large word-lengths. Those units are useful for applications that require high precision. There are however, many applications for which the use of reduced precision is sufficient. In those cases, one possibility is to use the large word-length arithmetic units to implement reduced precision operations with additional error detection. In this paper, this idea is explored for the case of matrix multiplications. A technique is presented and evaluated. The results show that it can detect most errors and that for large matrixes the overhead in terms of execution time is small.