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 · 中文 | PlayMemorize

一张纸只有 0.1 毫米厚，但每次折叠都会使厚度翻倍。这堆叠的高度增长有多快？

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需要折叠多少次才能让这张纸的厚度达到长颈鹿的高度？

为什么这么少: 翻倍增长惊人快速 · 0.1 毫米的纸张折叠 42 次即可到达月球。

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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