The great toilet-paper odometer
💡 by user: SymTech editorial team · 🤖 Built & fact-checked by AI · ✅ Human approved
Picture a mid-sized coastal town: 350,000 people, all with perfectly ordinary morning routines. Someone has to buy the paper.
The question — set by SymTech editorial
How many rolls of toilet paper does the whole town use in a year — and if you unrolled them into one strip, how far would it reach?
This one came from the SymTech editorial team — a human prompt, then the AI built and verified the exercise.
Estimate one person first: roughly one roll every three days. A roll holds ~200 sheets, which unrolls to about 20 metres.
Work it out
- 350,000 ÷ 3 ≈ 117,000 rolls per day.
- × 365 ≈ 43 million rolls per year.
- Unrolled: 43 M × 20 m ≈ 850,000 km.
- Earth's circumference ≈ 40,000 km.
- 850,000 ÷ 40,000 ≈ 21 laps.
About 43 million rolls a year — a soft white ribbon that would wrap the Earth 21 times.
What it teaches
Fermi estimation: shrink the town to one person, the person to one number per day, then multiply back up. Rough facts beat precise ignorance.
💡 Hermi's tip — make it yours
Count the rolls in your own bathroom for a week, multiply by 52, then by your household size and your city's households. The 43-million-roll figure is somebody's hometown maths waiting to be yours.