3QUESTION 3 OF 3
Answer & explanation
The official answer, with Fermi’s reasoning step by step.
Answer & explanation
Official answer
550,000
people
How to estimate it
Fermi’s official “Napkin math”
Ireland is a small country, about 5 million people. How many of them are actually redheads? Fewer than the stereotype suggests, maybe 1 in 10.
- Ireland's population
- 5,000,000
- Have red hair
- ≈ 1 in 10
- 5M ÷ 10
- ≈ 500,000
Rounded assumptions may give a slightly different estimate. The official answer above is the game’s reference value.
Source calculation & reference
- Republic of Ireland population
- 5,460,000
- Share with red hair
- ≈ 10%
- ≈
- 550,000
Reference cited by Fermi: 23andMe data on red hair among customers with four Irish-born grandparents
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.