Mine

Dim matrixA(,), matrixB(,), matrixP(,) As Integer
        Dim fillA, fillB As Integer
        Dim strA, strB, strP As String

        size = InputBox("Please Enter the size of the matrices")
        ReDim matrixA(Size, Size)
        ReDim matrixB(Size, Size)


        For i As Integer = 0 To (size - 1)
            For j As Integer = 0 To (size - 1)
                Randomize()
                fillA = Rnd() * 99
                matrixA(i, j) = fillA
                strA = strA & matrixA(i, j) & " "
            Next j
            strA = strA & Environment.NewLine
        Next i
        lblA.Text = strA

        For m As Integer = 0 To (size - 1)
            For n As Integer = 0 To (size - 1)
                Randomize()
                fillB = Rnd() * 99
                matrixB(m, n) = fillB
                strB = strB & matrixB(m, n) & " "
            Next
            strB = strB & Environment.NewLine
        Next
        lblB.Text = strB

        ReDim matrixP(size, size)

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

        lblC.Text = strP