matrix multiplication with design

public static Matrix operator *(Matrix A, Matrix B)
{
  if (A.Cols != B.Rows)
    return null;  // invalid matrices

  Matrix result = new Matrix(A.Rows, B.Cols);

  // iterate through rows of A
  for (int i = 0; i < A.Rows; i++)
  {
    // iterate through columns of B
    for (int j = 0; j < B.Cols; j++)
    {
      // iterate through rows of B
      for (int k = 0; k < A.Cols; k++)
      {
        result.Data[i,j] += A.Data[i,k] * B.Data[k,j];
      }
    }
  }

  return result;
}