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

紙の厚さは0.1mm、折るたび倍になる · キリン、エベレスト、月に届くまで何回折るか当てよう

紙の厚さはわずか0.1mmですが、折るたびに厚さが2倍になります。このスタックはどれほど速く伸びるでしょうか？

連続 0ベスト 0

キリンの高さに届くまで、紙を何回折らなければなりませんか？

なぜこれほど少ない: 2倍増加は驚くほど速い · 0.1mmの紙を42回折れば月に届きます。

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.

攻略ガイド

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.