Clock geometry: hands, angles, times

The minute hand sweeps 6 degrees a minute and the hour hand 0.5 degrees a minute, so the angle between them changes steadily and repeats. Nearly every clock problem is either an angle at a given moment, or a moment when the angle takes a given value.

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LearnWhat it is, how to spot it, a worked example, and where it goes wrong.
Practice — 3-point ladder1 problem. Three in a row finishes it.0/3 in a row · 0/1 solved
Practice — 4-point ladder1 problem. Three in a row finishes it.0/3 in a row · 0/1 solved
Practice — 5-point ladderNo problems written at this tier yet.Nothing written at this tier yet
Skill quizFinish every ladder that has problems first.Finish the ladders above first

Before and after

Needs first

GEO-05Angles on lines, in triangles, in polygons NUM-06Remainders and modular cycles

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Nothing yet. No other skill in the Atlas lists this one as a prerequisite.

In official papers

No indexed official paper question has been tagged with GEO-18 yet. The index grows one paper at a time, and it records only question numbers, point values and our own skill tags — never the problems themselves.

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