An easy question on climbing out of a well for P2–P3, with a step-by-step solution, diagrams and the answer. Rarely set directly in competition papers, but a classic for learning to think about the last step on its own. Good for the younger years.
The question
A well is 14 m deep.
A snail starts at the bottom: each day it climbs 3 m, and each night it slides back 1 m.
After sliding back on night 3, how high above the bottom is the snail?
Show the hints (2)
💡Hint 1: Over a whole day and night, how much higher does the snail really get?
💡Hint 2: By the end of night 3, how many whole days have passed?
Worked solution
Have a go first, then read the solution step by step.
1.Each whole day gains 3 − 1 = 2 m.
2.3 whole days: 3 × 2 = 6 m.
3.On day 3 it gets no higher than 7 m, still below the top at 14 m, so every night has its slide.
⚠️Common mistake: 3 × 3 = 9 m, forgetting the 1 m slide every night.
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