Explore
Fermi Problems
Good Fermi problems are answerable only approximately—but can be decomposed into quantities you can reason about.
Choose a problem below, make your estimate before opening the explanation, and compare your result with a reference answer.
Everyday life
- How much motor gasoline did the United States use per day in 2025?Estimate + reveal
- How many eggs did the United States produce per day in 2025?Estimate + reveal
Science
- How far is Earth from the Sun?Estimate + reveal
- How many lightning flashes happen worldwide each day?Estimate + reveal
Geography
- How many people lived in New York City in 2025?Estimate + reveal
- How many passenger journeys did airlines carry worldwide in 2025?Estimate + reveal
Technology
- How many functioning satellites orbited Earth in July 2026?Estimate + reveal
- How much electricity did data centers use worldwide in 2025?Estimate + reveal
- How many people used the Internet worldwide in 2025?Estimate + reveal
Business
- How many associates did Walmart employ worldwide in 2026?Estimate + reveal
- How many Starbucks stores were open worldwide in Q3 FY2026?Estimate + reveal
- How many Prime items arrived same or next day per day in 2025?Estimate + reveal