So, I added this because I think it's cool to compute 100,000! under second, but at the moment it's kind of an isolated example. You don't learn much comparing this program to a five line program in another language.
If it's worth keeping, it might be worth creating a separate task. I'll have to think about what that might be. Something like, "Use advanced techniques to compute a large factorial. Naive factorial algorithms bog down on most computers computing factorials over XXX or so. Implement an advanced factorial algorithm capable of quickly computing factorials over XXXX. Demonstrate your program computing a factorial near the limit of what is practical on your computer. Show timings, number of digits in your result, and the first 20 digits of your result. Describe or give a reference for your algorithm."
There are advanced algorithms out there besides Peter's. I dunno though. Maybe this is still too specialized for RC, or too big of a program for RC. ...just thinking...I'm new here yet.