Score
0
Best
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A figure flashes up and vanishes; turn a dial to the number you saw. Five angles, five length ratios and five split points, each flash shorter than the last, scored to a tenth of a point.
Tap Start. A figure appears for a moment and then hides. Drag your finger around the dial to set your estimate (clockwise raises it, anticlockwise lowers it), use − and + to nudge it by 1, then tap Lock. The true answer and your guess are drawn on top of each other before you tap Next.
A run is 15 rounds in three blocks of five. Rounds 1 to 5 ask for the angle between two rays in degrees. Rounds 6 to 10 show two bars and ask what percentage the short bar is of the long one. Rounds 11 to 15 show a line with a filled dot at one end and a mark somewhere along it, and ask how far along the mark sits, as a percentage measured from the dot.
The first figure stays up for 2.5 seconds and every round shows it 12% more briefly, so round 15 lasts only about 0.4 seconds. You can turn the dial while the figure is still visible, and there is no clock once it has gone: take as long as you like to settle on a number. The dial starts every round at 90° for angles and 50% for the other two blocks.
The dial is a jog wheel rather than a pointer: one full turn moves 90 degrees in the angle block and 50 percentage points in the ratio and split blocks, so a slow quarter turn is a fine adjustment. Holding − or + repeats the step. On a keyboard the arrow keys change the value and Enter locks it.
Each answer scores 100 × e^(−error ÷ 8) points, where the error is the distance from the true value in degrees or percentage points. A perfect answer is worth 100, an error of 2 about 77.9, 4 about 60.7 and 8 about 36.8. The true values are not whole numbers but your answer is, so even a flawless eye drops a little each round. Your total over the 15 rounds is shown to one decimal place, and the result card lists your average error for each block.
Anchor angles on the landmarks you already know. Almost everyone can spot 90°, 45° and 180° reliably, so judge the figure as "a bit past a right angle" or "half of 45" and then convert, rather than guessing a raw number. The arc drawn in rounds 1 and 2 disappears from round 3 onward and the rays start to differ in length; ignore ray length entirely, because only the opening between them counts. Beware of mirror images: from round 2 the second ray may open clockwise or anticlockwise, which changes nothing about the size.
For the ratio block, picture laying the short bar along the long one. In round 6 they start at the same left edge, which is the easy case; after that they are offset, then one stands upright while the other lies flat, then both tilt. Vertical lengths tend to look longer than equal horizontal ones, so when the short bar is the upright one, shade your estimate down a little. In the last ratio round the two bars also have different thicknesses, and a fat bar tends to look longer than it is.
For the split block, halve and halve again. Ask first whether the mark is before or after the middle, then which quarter it falls in, and only then refine inside that quarter: 37 becomes "a bit under three eighths". Always check which end carries the filled dot, because from round 12 it can be on either side, and from round 13 the line tilts, which removes the help of the screen edges.
Because the score falls away exponentially, one wild answer costs far more than several small slips: being out by 20 earns about 8 points while being out by 4 still earns about 61. When a figure slips past too quickly, commit to the safe middle of your range rather than gambling on an extreme. And use the time after the flash: there is no clock while the figure is hidden, so turn the dial slowly, check the number once more, then lock.