Strange rounding errors?

I have a matrix A(7,7) with different real values.

If I do:

Test1=sum(sum(40*A));

Test2=40*sum(sum(A));

I get slightly different values for Test1 and Test2 (Test1-Test2=1e-8 or so)

In cases of simple matrix elements like numbers 1,2,3,etc. this doesn't happen. With my entries though, which are different in size...

Now I suppose this behaviour is due to rounding errors...What would be best? If I use Test2 for calculations?

Or is there something I misunderstood?