I have the honor to know Roberto Mensa via Linked In. He is strongly committed to explore, develop, improve and to discuss formulas in Excel. The site is fully dedicated to Excel formulas. If You’re serious about MS Excel then this site is a must. Of course, he is not alone, another great contributor is Krisztina Szabó aka Kris.
The virtual spot has the name E90E50 fx. I have no ideas for what it stand for…
Anyway, You may start at the following point: E90E50 fx.
The link points to the main page. However, the latest contribution is Combinatorics using Excel formulas.
Make sure You have some hours free to take part of the contribution. Don’t forget to bring coffee to the computer.
Enjoy and have a nice Easter Weekend!