simple - moblog the next number in the sequence.
No computer screenshots, or staged photos (ie: writing the number, arranging objects etc..) otherwise it's too easy. The challenge lies in spotting the number somewhere and snapping it before someone else gets there first. So, no cheating - unless you're particularly clever or funny, in which case you might get away with it.
Posted by retrogal
Posted by 540air
Posted by si_round