Tried looking it up and it got complicated real quick.
In: Physics
The basic answer is a kilogram of uranium contains something like 10^24 atoms. That’s a million billion billion.
It’s enough that even an individual atom only has a 50% chance of splitting over 4.5 billion years, there are enough atoms splitting over a reasonable amount of time that you can measure thr decays and use math to figure out the rest.
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