missing dollar problem
Three people have dined at a restaurant and received a total bill for $30.
They agree to split the amount equally and pay $10 each. The waiter hands
the bill and the $30 to the manager, who realizes there's been a mistake
and the correct charge should be only $25. He gives the waiter five $1 bills
to return to the customers, with the restaurant's apologies. However, the
waiter is dishonest. He pockets $2, and gives back only $3 to the customers.
So, each of the three customers has paid $9 and the waiter has stolen $2
making a total of $29. But the original bill was for $30. Where has the
missing dollar gone? (See solution below.)
A version of this problem first appeared in R. M. Abraham's Diversions
and Pastimes in 1933.1 See also nine
There is no missing dollar (of course!). Adding $27 and $2 (to get $29)
is a bogus operation. They paid $27, $2 went to the dishonest waiter, and
$25 went to the restaurant. You have to subtract $27 minus $2 to get $25.
There never was a $29; it's a phony calculation designed to confuse the
- Abraham, R. M. Diversions and Pastimes. London: Constable
& Co., 1933. Reprinted , 1964.