How many does it take?

How to play

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  Five experiments a day. How many balloons lift a cat? How many batteries boil a kettle? Each one says its assumptions up front.

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  Slide to your guess and try it. The experiment runs with your number: not enough, too many, or just right. You get three tries.

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  3 points for a first-try hit, 2 for the second, 1 for the third. Up to 15 a day, then share and come back tomorrow.