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Primes

by yellowho » Mon Feb 14, 2011 7:42 pm
How many integers from 1 to 901 have exactly three positive divisors, which are 1, the
number itself, and a prime number?

Counting primes squared is the only way to do this? 30^2= 900, so all the primes below 30?
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by Night reader » Mon Feb 14, 2011 8:03 pm
this is correct {2,3,5...29}
yellowho wrote:How many integers from 1 to 901 have exactly three positive divisors, which are 1, the
number itself, and a prime number?

Counting primes squared is the only way to do this? 30^2= 900, so all the primes below 30?
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