Matrix **A** can be multiplied by a matrix **B** if the number of columns of matrix **A** equals the number of rows of the matrix **B**.

**Matrix multiplication** (**product of matrices**) **A** and **B** with dimensions m×n and n×k is the operation of finding the matrix **C** with size m×k, all of whose elements are equal

$c_{ij} = \sum_{k=1}^n a_{ik} b_{kj}$