We're on the middle of the most devastating war the Earth has gone through all its history. You and your brother in arms are in a plane that has been taken down while crossing the enemies lines. You are okay, but your teammate has a head contussion and must be immediately brought back to your base.
Luckily, you are such a great pilot that the aircraft has nearly no damage and can fly again, but one of the two fuel tanks was lost due to the accident. Furthermore, the on-board computer has stopped working so it can't help you. You want to know if you can get your friend back to the base with the fuel you have. In the middle of your calculations, you find that you can't remember any of the digits of $\pi$, which you need to calculate the distance from where you are to your base (taking the Earth as a perfect Sphere) in order to estimate the fuel needed. There is nothing inside the plane which can help you with the calculation, so you have to stick to the next items.
You can ONLY use to calculate it:
- Your belt, which has a length of 1 metre.
- Some rocks you found near the plane.
- A wooden stick. You can use it to draw or anotate numbers on the ground.
Luckily, you can come up with a way to get a pretty good approximation of $\pi$ and be able to know if you can save your friend's live. Each second counts...