Lowest Average Error Estimating Ten Angles

China

Be the first to like this record

About

Beihu-Chenzhou-Hunan, SAR, China / October 30, 2026

Yanhao Deng of Chenzhou, China, judged ten random angles in a row by eye on a phone angle-estimation test, setting each guess on a slider before the true angle was revealed. The screen recording runs from the countdown to the final report with each true angle shown next to the guess, and the ten misses of 5, 7, 8, 1, 2, 0, 3, 7, 2 and 10 degrees, including a dead-on call of 96 degrees, average out to 4.5 degrees, which the test rounds to 5. No protractor needed, just a very well-calibrated eye.

Tags: online game, math, lowest, Brain Training, geometry, angles

Rules

- Ten angles in one continuous run of an on-screen angle-estimation test, recorded from the start of the run to its final result with no cuts.
- Each angle is picked at random by the test to the whole degree, anywhere under 180 degrees. Tests that only use round numbers, such as multiples of 5 or 15, do not count.
- Estimate by eye only: no protractor, ruler, measuring app, angle readout, or preview of the guess drawn over the angle. A plain or gridded background is allowed.
- Each guess is locked in before the true angle is shown, and the test shows the true angle and the guess for all ten angles.
- The result is the average of the ten errors in degrees (how far each guess was from the true angle, over or under), worked out from the values on screen to one decimal place. Lower is better.
Comments
Under review comments