Matrix multiplication is one of the most commonly used algorithm in many applications including operations on relations in relational database system. In this paper, the authors study and evaluate the execution time of matrix multiplication on a single, dual and multi-core processor with same set of processors having OpenMP (Open Multi-Processing) libraries for C-language. OpenMP is a very well-known standard that exploits parallelism in shared memory architecture. The evaluation is based on execution of the algorithm uses single thread for computation whereas the one with OpenMP uses multi-threads.