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 3 m deep.
A snail starts at the bottom: each day it climbs 2 m, and each night it slides back 1 m.
As soon as it reaches the top during a day, it is out and does not slide back.
On which day does the snail get out?
Show the hints (2)
💡Hint 1: Keep track day by day: how high is it by the end of each day, and after each night?
💡Hint 2: On the day it reaches the top it is out — no sliding back that night.
Worked solution
Have a go first, then read the solution step by step.
1.Each full day and night gains 2 − 1 = 1 m.
2.After night 1 the snail is at 1 m.
3.On day 2 it needs only 2 m more and can climb 2 m, so it gets out on day 2.
⚠️Common mistake: working out 3 ÷ 1 and answering day 3, forgetting there is no slide after the last climb.
Play more like this in Numsprite (unlimited questions, instant marking) →A free maths game: every level free from Easy to Expert (★ to ★★★★), unlimited questions, no download