Answer & explanation
The official answer, with Fermi’s reasoning step by step.
Answer & explanation
Official answer
9
clock towers
How to estimate it
Fermi’s official “Napkin math”
The Burj Khalifa in Dubai is the world's tallest building, about 800 meters. How tall is Big Ben's tower? Maybe 100 meters, about a 30 storey building.
- Burj Khalifa
- ~800 m
- Big Ben's tower
- ~100 m
- 800 ÷ 100
- ≈ 8
The Burj Khalifa in Dubai is the world's tallest building, a little over half a mile, call it 2,700 feet. How tall is Big Ben's tower? Maybe 300 feet, about a 30 storey building.
- Burj Khalifa
- ~2,700 ft
- Big Ben's tower
- ~300 ft
- 2,700 ÷ 300
- ≈ 9
Rounded assumptions may give a slightly different estimate. The official answer above is the game’s reference value.
Source calculation & reference
- Burj Khalifa height (CTBUH Skyscraper Center)
- 828 m
- Elizabeth Tower height (UK Parliament)
- ÷ 96 m
- 828 ÷ 96
- ≈ 8.6
- 8 towers fall short, so it takes
- 9 towers
Reference cited by Fermi: CTBUH Skyscraper Center (Burj Khalifa, 828 m); UK Parliament (Elizabeth Tower, 96 m)
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