In this paradox no contradiction is actually taking place. There is no missing dollar. Adding $27 and $2 (to get $29) in the end is not required at all. The ladies paid $27 out of which $25 went to the restaurant and $2 went to the waiter. Actually we are supposed to subtract $2 from $27 and not add it to $27 . Adding $27 and $2 to get a $29 is just an additional calculation to confuse everyone.