# if it takes 20 days for an atom to reach its half life. how much days would it take for it to decay 1/8 of the initial atom?

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- VamanLv 71 year agoFavorite Answer
Let us take 32 atoms. After 20 days it is now half. So it is 16 now. Another 20 days it will be 8. After another 20 days, it will be 4. 4 is 1/8 of 32. So you need 3 times 20 days. I think it will be 60 days.

- Markus ImhofLv 71 year ago
Doesn't work that way - any atom can only decay once (ok, apart from decay chains). For a sufficiently large number of atoms (several thousand, at least), billrussel42's answer is correct. But the concept of half-life always applies to large numbers of atoms, not individual ones.

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