1QUESTION 1 OF 3
Answer & explanation
The official answer, with Fermi’s reasoning step by step.
Answer & explanation
Official answer
360,000
people
How to estimate it
Fermi’s official “Napkin math”
Start with the world's population, about 8 billion. People are spread across ages from 0 to about 70. How many are any one age? 8 billion ÷ 70, about 115 million. They all have a birthday somewhere in the 365 days.
- World population
- 8,000,000,000
- ÷ ~70 years of age
- ≈ 115,000,000
- ÷ 365 days
- ≈ 315,000
Rounded assumptions may give a slightly different estimate. The official answer above is the game’s reference value.
Source calculation & reference
- Babies born worldwide in 2008 (UN World Population Prospects 2024)
- ≈ 141,800,000
- Still alive at 18 (UN IGME: 5.5% died before 5, about 1% more by 18)
- × 93%
- 132M ÷ 366 days (2008 was a leap year)
- ≈ 360,000
Reference cited by Fermi: UN World Population Prospects 2024: about 142 million births worldwide in 2008
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.