Prime number in set $\{1,...,60\}$

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How can we calculate by using the principle of inclusions and exclusions how many prime numbers are in the set $ \{1, ..., 60 \} $?

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Observation: Any composite number between 2 and 60 has a prime factor less than $\sqrt{60}$. So any composite number in that range must be divisible by 2, 3, 5 or 7. What is the number of composites in this range then?