Mine

For p As Integer = 0 To size - 1
            For q As Integer = 0 To size - 1
                For r As Integer = 0 To size - 1
                    matrixP(q, p) = matrixP(q, p) + (matrixA(r, p) * matrixB(q, r))
                    strP = strP & matrixP(q, p) & " "
                Next
            Next
            strP = strP & Environment.NewLine
        Next