Howdy, formula boffins. Thought you might be interested about a series I started over at http://chandoo.org/forums/forum/excel-challenges

You’ll find a whole bunch of tricky formula challenges posted by a group of excel nerds (me included) trying to out-nerd each other with formula nerdiness.

I also wrote up a series of blog posts covering this inaugural challenge, with the first one at http://chandoo.org/wp/2013/07/16/for...allenge-001-1/ (The next three posts are scheduled to be posted over the coming week).

These are great learning opportunities. For instance, a dude just posted another solution in the comments of this first post that uses a pandigital number. Very cool concept. See http://en.wikipedia.org/wiki/Pandigital_number

Have at it!