Fermi estimate
Definition · Level 11 · Interview practice
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An order-of-magnitude answer built by breaking an unknown quantity into factors you can guess, rounding each, and cross-checking with a second route.
Example
Petrol stations in France ≈ 2M fills a day ÷ 200 fills per station ≈ 10,000.
Where Tradecraft teaches it
Level 11 · Interview practice, in the lesson “Estimation (Fermi) questions”: Scope it, break it down, round hard, and sanity-check with a second route.
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