level 8
剑雨江南2
楼主
Three men went to a hotel to share a room.
The clerk asked for $300.
Each man paid $100, making up the $300.
The hotelkeeper then decided to allow a discount for the day, charging only $250 for the room.
He told the clerk to return $50 to the three men.
The clerk pocketed $20 for himself. He gave the remaining $30 back to the three men.
Each man took back $10. Therefore, each man paid 100 - 10 = $90 to the hote1l
$90 x 3 = $270 + the clerk's $20 = $290.
Question: Where has the remaining $10 gone?
There is widespread interest in this question posted by a university in N.Z.
Many people are still trying to work out an answer
