http://digicc.com/fido/

I can't figure it out yet, but it works...

 

Computers are really good @ math. There is not trick, There is a Math forumla in there somewhere

 

I thought i would try a fast one on it but...


I thought i would try a fast one on the program...
started with 112 mixed it to 121 subtracted 112 for 9 as the mystery number, and was unable to enter a number so i put in o and it answered 9


a good math formula, as ccla said.