Interactive tool
Fermi Trainer
Chain your assumptions → an order-of-magnitude estimate.
OPEN DT-11 · FERMI ESTIMATION: PRODUCING A NUMBER WHEN YOU HAVE NO DATACLIENT-SIDE · NOTHING SENT
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Interactive tool
Fermi Trainer
Nothing you type is sent anywhere.
Break it into factors you can guess. Multiply, don't agonise — the goal is the right order of magnitude, not the right number.
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Estimate
40,000
Order of magnitude ≈ 10^4. If the true answer is within a factor of ten of this, your estimate did its job.