Question: Multiplying Eigenvalues

Question: Generate 8 random 3 by 3 matrices using the RandomMatrix command from the  LinearAlgebra package. As each matrix is generated use Eigenvalues to compute its eigenvalues. Then take the product of the eigenvalues, and check that for each matrix, this product is equal to the determinant of the matrix.  

[Hint: The product will be complicated algebraically and you will need to apply first expand, then simplify to reduce the product of the eigenvalues to an integer. First try to do for a single matrix , then make a loop to do it 8 times.]  

Attempt:
> with(LinearAlgebra):

    for i from 1 to 8 do  

    M[i]:=RandomMatrix(3,3):  

    N[i]:=Eigenvalues(M[i]):    

   simplify(N[i]):
   end do:

   evalf(N[i].N[i]);
When I change the 8 from 1-7 I get a number, but once I change it to 8 I get "N 2(over)9" 

can I get any suggestions