MAKE AN ESTIMATE. LEARN FROM THE GAP.
Fermi Estimation Game
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About Fermi Estimation Game
Make three educated number estimates, reveal sourced answers and learn from symmetric error scores. Unlimited Fermi estimation practice by Word Trail.
New rounds draw unanswered questions or target objects first. A final new round may be shorter. After the bank is exhausted, choose Replay this round to revisit it explicitly. There is no timer or daily schedule. Reference objects may recur; different pairs are not independent new facts. Refresh restores submitted answers; an unsubmitted adjustment is not saved.
What is a Fermi problem?
A Fermi problem uses simple assumptions and rough arithmetic to estimate a quantity. These Fermi questions combine published facts with explicit models: aim for the right order of magnitude, then use each explanation to improve your reasoning. This number estimation game is free to play.
Frequently asked questions
Do I need the exact answer?
No. Getting the scale right is the challenge. Twice too high and twice too low both produce 2× error and 50 points.
Are all answers measured facts?
No. Some are published facts; others are original calculations under assumptions stated in the question. The reveal explains which applies.
Is this Fermi.gg?
No. This is independent Word Trail practice with original questions and code. It is not affiliated with Fermi.gg and does not provide that site’s answers.
Can I share my score?
Complete the round and choose Copy result. If clipboard access is unavailable, select the displayed text. Sharing is your choice; no result is posted automatically.
Sources and original work
Thirty original English questions include published facts and clearly stated calculation models. Each answer reveal links to its source and shows the calculation.
- nssdc.gsfc.nasa.gov · reference
- www.nist.gov · reference
- www.toureiffel.paris · reference
- www.nps.gov · reference
- www.nps.gov · reference
- www.parliament.uk · reference
- cms.nba.com · reference
- www.nist.gov · reference
- www.nist.gov · reference
- tsapps.nist.gov · reference
Report a measurement or control problem
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