Count Sandini calls himself the greatest "Sand Counter" in the world. Show him a bucket filled of sand, and in a few seconds he will tell you how many grains of sand are there!
Can you devise a (fairly quick) test to prove whether he can actually do so, or if he's a fraud?
Show Count Sandini a bucket of sand and obtain an aswer from him.
Remove some reasonably countable number of grains from the bucket (maybe 2050) without letting him see how many were removed.
Ask the Count to tell you how many are now in the bucket. If his new answer plus the number of grains you removed is equal to his earlier answer, then you have some assurance that he really is the greatest "Sand Counter".

Posted by Erik O.
on 20050407 15:47:59 