Snail in a Well

This is a famous problem; you may have seen it. It appeared in an arithmetic textbook published in Nuremberg in 1561; Stella thinks that this was the first time it appeared in print. Anyhow, the problem is this: A snail has fallen into a dry well 21 meters deep. It starts climbing up the side of the well so as to escape. Each day it climbs 7 meters, but each night it slides back 2 meters. If it starts climbing on July 1, on which day will it finally be out of the well?

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Pirate Queen

Pirate Queen Goldie is pacing the deck of her ship, the Vasa II. She is waiting for her first mate, Waugamon, to return from burying the treasure. There is a rope ladder hanging over the side of the ship so Waugamon can get back on board when he returns. The ladder has rungs that are exactly one foot apart. There are 15 rungs on the ladder and the lowest one just reaches the level of the water below. The Pirate Queen waits and waits, and the tide comes in—the water level rises three and one-half feet. If Waugamon comes back now, how many rungs on the ladder will he have to climb to get on board the ship?

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