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Brainteasers

Half a jug with no markings

measuringlateral-thinkinggeometry

You have a plain cylindrical glass with straight sides and a flat bottom, no markings anywhere, a tap, and nothing else: no ruler, no second container, no scale.

Fill the glass exactly half full. Your method must be exact, not an eyeball estimate.

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Straight sides mean the glass has a symmetry. Water finds its own level, even when the glass is not upright.

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