19 random digits is not enough to uniquely identify all human beings

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Suppose that you assigned everyone an 19 digit number. What is the probability that two human beings would have the same number? It is an instance of the Birthday’s paradox.

 

Assuming that there are 8 billion people, the probability that at least two of them end up with the same number is given by the following table:

 

 

If you want the probability to be effectively zero, you should use 30 digits or so.

 

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