How is the number of folds worked out?

A sheet of paper is 0.1 mm thick and every fold doubles it, so the height after n folds is 0.1 mm times two to the power n. The answer is the smallest whole number of folds whose stack reaches the target height · mathematically, the ceiling of log base 2 of the height divided by 0.1 mm.

Does folding paper 42 times really reach the Moon?

In theory, yes. 42 doublings of a 0.1 mm sheet is about 440,000 km, which clears the average Earth-Moon distance of roughly 384,400 km. In practice you cannot fold ordinary paper more than about seven or eight times · the game is about the maths of doubling, not a folding challenge.

Are the object heights real?

Yes · they are the widely-cited real heights or distances for each object, from a giraffe at about 5.5 m to the edge of space, the Space Station and the Moon. The reveal shows the height it used.

Why do such tall things need so few folds?

Because doubling is exponential. Ten folds already gives about a metre, twenty folds about a kilometre, thirty folds about 1,000 km · each ten folds multiplies the height roughly a thousandfold, so even huge heights fall within a few dozen folds.

Does it work offline?

Yes. PlayMemorize is a Progressive Web App, so Paper Folds keeps working without a connection once the page has loaded.

Paper Folds · 한국어

종이 한 장은 두께가 0.1mm에 불과하지만, 접을 때마다 두께가 두 배가 됩니다. 이 쌓이는 높이는 얼마나 빨리 올라갈까요?

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기린 높이까지 도달하려면 종이를 몇 번 접어야 할까요?

왜 이렇게 적게?: 두 배 성장 속도는 놀랍게 빠릅니다 · 0.1mm 종이를 42번 접으면 달까지 도달할 수 있습니다

Guess how many times you must fold a sheet of paper for it to reach the height of real objects · from a giraffe to the Moon. JavaScript required.

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