the 4th term is a(4)
by the definition:
a(4) = a(3) * 10
we need a(3)!
a(3) = a(2) * 10
we need a(2)!
a(2) = a(1) * 10
Ah we know that a(1) = -11! Now we can go back to a(4).
So now we know that a(2) = -110,
that a(3) = -1100,
And that a(4) = -11000
there's the answer
