The Extra Dollar

Here is an old math puzzle that you can find many versions of online.

Two friends have a meal at a restaurant, and the bill is $25. The friends pay $15 each, which the waiter gives to the cashier. The cashier gives back $5 to the waiter. The friends tell the waiter to keeps $3 as a tip, so he hands back $1 to each of the two diners.

So, the friends paid $14 each for the meal, for a total of $28. The waiter kept $3, and that makes $31. Where did the extra dollar come from? Give yourself a moment to think about it before clicking below for the solution.

$25 is sitting with the cashier, $2 is back with the diners, and $3 is with the waiter. That adds to the required $30, so there really is no extra dollar.

The mistake is expecting that what the diners paid and what the waiter kept to add up to what they initially gave. Adding $28 and $3 is just a bit of sleight-of-hand. It's the amount that the meal effectively cost them (including tip), plus the amount they received back, that should add to $30.