0 setn r10 100 # Initialize stack pointer
1 read r2 # Get N
2 calln r9 5 # Recursive function finds N!
3 write r1 # Write result
4 halt
# Function to compute N! recursively . N is in r2 . N! is in r1 .
5 jeqzn r2 18 # Test for base case (0!)
6 addn r10 1 # Save precious possessions
7 storer r2 r10 # ...
8 addn r15 1 # ...
9 storer r9 r10 # ...
10 addn r2 -1 # Calculate N - 1
11 calln r9 5 # Call ourselves recursively to get (N - 1)!
12 loadr r9 r10 # Recover precious possessions
13 addn r15 -1 # ...
14 loadr r2 r10 # ...
15 addn r10 -1 # ...
16 mul r1 r1 r2 # (N - 1)! times N
17 jumpr r9 # Return to caller
# Base case : 0! is always 1
18 setn r1 1
19 jumpr r9 # Return to caller