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

0.1mm 종이는 접을 때마다 두 배 · 기린, 에베레스트, 달까지 몇 번 접어야 하는지 맞혀 보세요

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

연속 0최고 0

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

FAQ

About Paper Folds

Paper Folds is a small lesson in how fast doubling runs away from you. A sheet of paper is about 0.1 mm thick, and every time you fold it in half the thickness doubles. The game names a real object · a giraffe, the Eiffel Tower, Mount Everest, the Moon · and asks how many folds it would take for the stack to reach that height. Four choices; pick the closest.

The answer is exact maths, not a guess. The number of folds is the smallest whole number of doublings that reaches the target height: ceil(log2(height ÷ 0.1 mm)). Because the growth is exponential, the answers are absurdly small · a giraffe takes about 16 folds, Everest about 27, and the Moon a mere 42. The reveal shows the object's real height and the fold count every round.

Build a streak. Each correct answer grows your streak and your best is kept, so a run trains your intuition for exponential growth · the same maths behind compound interest and viral spread.

Part of the PlayMemorize family · runs entirely in your browser and works offline as a Progressive Web App.

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FAQ

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.