35889

We used the Fibonacci Sequence to find the answer to this problem.
We decieded to see how many ways there were for 2 steps then go up to 12 steps.
These are the answers that we got

2 steps= 2 ways
3 steps= 3 ways
4 steps= 5 ways
5 steps= 8 ways
6 steps= 13 ways
7 steps= 21 ways
8 stpes= 34 ways
9 steps= 55 ways
10 steps= 89 ways
11 steps= 144 ways
12 steps= 233 ways

Therefore there are 233 possible ways to go down 12 steps using 1 or 2 steps at a time.