Alfred is at the bank to cash his $200 check. He tells the cashier he would like some one dollar bills, ten times as many two dollar bills and the rest in fives.
How many of each denomination does the cashier need to give Alfred?
We know that in order to give the rest of the amount in fives, the sum of the one and two dollar bills needs to be divisible by five (i.e. end in 0 or 5).
If we start with a single one dollar bill, we’d need ten two dollar bills to satisfy the request, making $21. But we need a sum that is divisible by 5. So we keep going up, like so:
Mary was out riding a frisky pony in a meadow by the sea when the bridle came loose. The animal shook it off and started to gallop full speed toward the ocean, paying no attention to Mary’s yelling to slow down. She couldn’t bear to jump off and lose her beloved pony, so she stayed on and hoped for the best. When the cliff loomed ahead of her, she knew she had to stop the pony. How did she do it?
A harvest sown and reaped on the same day In an unplowed field, Which increases without growing, Remains whole though it is eaten Within and without, Is useless and yet The staple of nations.