A snail is at the bottom of a 10 m well. Each day it climbs 3 m, and each night it slides back 2 m. How many days until it gets out?
Hint: On the last day it doesn't slide back.
8 days.
After 7 days it's at 7 m. On day 8 it climbs 3 m to reach 10 m and is out before night.
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