2QUESTION 2 OF 3
Answer & explanation
The official answer, with Fermi’s reasoning step by step.
Answer & explanation
Official answer
3,428
billionaires
How to estimate it
Fermi’s official “Napkin math”
The easiest place to start is the world's population, about 8 billion. How rare is a billionaire? Much rarer than one in a million. Call it 1 in every 2 million people.
- World population
- 8,000,000,000
- Is a billionaire
- ~1 in 2 million
- 8B ÷ 2M
- ≈ 4,000
Rounded assumptions may give a slightly different estimate. The official answer above is the game’s reference value.
Source calculation & reference
- US billionaires
- 989
- Everywhere else
- + 2,439
- 989 + 2,439, net worths as of March 1, 2026
- = 3,428
Reference cited by Fermi: Forbes, The World's Billionaires 2026 (published March 10, 2026)
How close was your guess?
Your comparison will appear here.
Compare by ratio: divide the larger number by the smaller one. The closer to 1×, the better.