<P> From the owner point of view the correct solution is this: 1) First day: $20 owner already withdrew + $30 in the bank = $50 2) Second day: $20 owner already withdrew+ $15 owner already withdrew + $15 in the bank = $50 3) Third day: ($20 owner already withdrew + $15 owner already withdrew + $9 owner already withdrew) + $6 in the bank = $50 </P> <P> The solution appears very obvious if the owner withdraws every day only $10 from $50 . To add up 40 + 30 + 20 + 10 using the same pattern from above would be too obviously wrong (result would be $100). </P> <P> The answer to the question, "Where did the extra dollar come from?" can be found from consecutively adding the bank rest from three different days . This way is correct only if the money owner withdraws every day exact half of the money . Then it will add up . ($25 + $12.50 + $6.25) + $6.25 = $50 </P> <P> Another entry from 1933, R.M. Abraham's Diversions and Pastimes (still available in a Dover version) poses a slightly different approach with this problem from page 16 (problem 61). "A traveller returning to New York found that he had only a ten dollar postal money order, and that his train fare was seven dollars . The ticket clerk refused to accept the money order, so the traveller went across the road to a pawn shop and pawned it for seven dollars . On his way back to the station he met a friend, who, to save the traveller the trouble of returning to redeem the money order, bought the pawn ticket from him for seven dollars . The traveller then bought his ticket and still had seven dollars when he got to New York . Who made the loss?" David Darling in his The Universal book of Mathematics, credits this as an earlier version of the three men in a hotel version above . </P>

Where did the extra $1 come from