Fermi, at fermi.gg, is a daily estimation game named after the technique Enrico Fermi popularized of reaching hard numbers through quick math and reasonable guesses. Each day brings three questions, such as the number of iPhones made since the 2007 launch, and you get one guess at each, with a built-in calculator but no searching. Scores are multiples of the true answer, so 1x is perfect and lower beats higher. Each reveal comes with sample napkin math you could have used.
How Many comes first, a quick count-the-crowd estimate with a crowd average to compare against, followed by Magnitudle, which shares Fermi's multiplicative view of error. After those are other daily number questions, then estimates aimed at weights, auction prices and objects you can see, where the arithmetic gives way to judgment by eye.
A gut-instinct estimate without the arithmetic: a flash of beans, stars or sheep appears only briefly, you put a number on the crowd, and the average of all players' guesses follows, much like Fermi's comparison with other players.
Shares Fermi's logic most closely: a single daily question about a real quantity, answered with a number and a magnitude button running up to quadrillions, and graded on how many powers of ten separate you from the truth.
Three estimation questions, as in Fermi, but scored from 100 points with each gap from the truth subtracted, so a single wild miss can wipe out the round, a choice that punishes big misses differently from Fermi's multiples.
Prices instead of quantities: five historical items, one guess apiece, judged on the size of the miss relative to the real price, which is close in spirit to Fermi's habit of measuring error as a ratio.
Five number questions on a slider, worth as much as 200 points each for coming close. One asked for the span of the Pantheon's dome from the inside, exactly the kind of figure Fermi's napkin math is built for.
Five weighings a day, each asking how many of one thing would balance another, with pairings as lopsided as grapes and giraffes or paperclips and rockets, so splitting the problem into steps pays off.
Uses a scale too: five heavy objects, each to be matched by a number of household-scale things like cats or bowling balls, a close counterpart to Tilt with everyday units of comparison.
Estimates money rather than counts: five real U.S. government surplus lots, each with photos and details to flip through, and a guess at what it sold for at auction, with full points inside 5 percent.
A slider quiz of five number questions where every notch you miss by costs a point out of 100, followed by a look at how other players guessed, similar to Fermi's view of where you landed in the field.
A single focused estimate: the piece count of a LEGO set, judged from a look at the set and refined over as many tries as you need, which turns Fermi-style reasoning into a homing-in game.
Pictures of a filled container, pasta in a tub being one, and three goes at counting the pieces inside, practice for the kind of reasoning a question about tennis balls in a school bus calls for.
As a multiple of the real answer. A perfect guess scores 1x, missing by double scores 2x and being ten times off scores 10x, so lower is better, and your result for the day is the average of the three questions. After each answer you also see how everyone else guessed and some example math you could have used.
Yes. A calculator is built in, and you open it by tapping its icon while you work on a guess. Searching for the answer is off limits, though, since the point is napkin math and gut instinct. A new set of three questions appears every day at midnight Eastern time, and older puzzles live in the archive.
Yes. The site has a form for question ideas, with sample prompts like the price of a pool full of milk or the number of tennis balls a school bus could hold, and every submission is reviewed. Including where the question comes from and what the answer is makes an idea easier to use.
