Wonderful.

My version of iml doesn't have the LFACT finction , so I used
log(fact(n)). However, i couldn't get past 170!

At 180!, my saslog said,

802 f = BigF(180);
ERROR: (execution) Invalid argument to function.
. . . .

NOTE: Exiting IML.
NOTE: 8 workspace compresses.
NOTE: PROCEDURE IML used (Total process time):
real time 0.04 seconds
cpu time 0.04 seconds

So I guess I hit the limit of my laptop.

Al