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 Sandini a bucket filled with sand and get his count; then take out a known amount of sand, then get his count again. Repeat the procedure one more time. If the difference matches then it would sufficiently prove his legitimacy.
Puzzle Thoughts
