How to play

Every day at midnight Eastern, Zoggle serves three questions with numerical answers — things like “How many commercial flights take off worldwide on a typical day?” You won't know the exact answer. That's the point. Your job is to estimate: reason your way to a number that's in the right neighborhood.

Scoring — lower is better

Your score on each question is how many times off your guess was, in whichever direction. Guess 50,000 when the answer is 100,000 and you're 2× off. Guess 200,000 — also 2× off. A perfect guess scores 1×. Your daily score averages the three questions (a geometric mean, so one wild miss can't hide).

• 🎯 1× — Bullseye. Suspiciously good.
• 🟢 under 2× — Excellent estimation.
• 🟡 under 10× — Right order of magnitude. Respectable.
• 🟠 under 100× — One order off. It happens.
• 🔴 100× or more — Cosmic miss. Tomorrow is a new day.

How to estimate anything

The trick — named for the physicist Enrico Fermi, who was famous for it — is to break an impossible question into pieces you can roughly guess. How many piano tuners in Chicago? Well: how many people live there, how many households have pianos, how often does a piano need tuning, how many tunings can one person do in a year. Multiply your rough pieces, and errors tend to cancel out. Getting within 10× by pure reasoning is a genuine skill, and it's trainable. That's what the daily habit is for.

There is a proper method to this, and it is learnable — start with how to estimate anything, or see it applied in the piano tuner problem.

The fine print

• One guess per question. No edits, no retries — commit like you mean it.
• Shortcuts work in the answer box: 250k, 1.5m, 3b, 2e12.
• There's a calculator under the answer box for scribbling — using it is not cheating, it's technique.
• Looking up the answer is cheating, though. You know it, we know it, and the only person whose streak goes hollow is you.
• Your streak and history live in your browser. No account needed.