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Math question

Can someone help me with this question??
How many positive integer divisors of 2004^2004are divisible by exactly 2004 positive integers?

Reply 1

Original post
by yi123456
Can someone help me with this question??
How many positive integer divisors of 2004^2004are divisible by exactly 2004 positive integers?

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I understand the first part, but I don’t really get the second part about counting

Reply 2

Original post
by yi123456
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I understand the first part, but I don’t really get the second part about counting

Do you understand where (x+1)(y+1)(z+1) comes from?

Reply 3

Original post
by mqb2766
Do you understand where (x+1)(y+1)(z+1) comes from?

Yeah (just until there)

Reply 4

Original post
by yi123456
Yeah (just until there)

From there on its just a simple diophantine/integer equation so
(x+1)(y+1)(z+1)=2004
as the lhs represents the number of distinct factors/divisors, so prime factorise the rhs (which youve already done) and then consider how many different ways you have for equating the factors of the right to the terms on the left.

Reply 5

Original post
by mqb2766
From there on its just a simple diophantine/integer equation so
(x+1)(y+1)(z+1)=2004
as the lhs represents the number of distinct factors/divisors, so prime factorise the rhs (which youve already done) and then consider how many different ways you have for equating the factors of the right to the terms on the left.


What I don’t really understand is how they’ve calculated the number of different ways when equating factors - I thought it would be sth like 3*2*1 (permutations?)

Reply 6

Original post
by yi123456
What I don’t really understand is how they’ve calculated the number of different ways when equating factors - I thought it would be sth like 3*2*1 (permutations?)

Sometimes its useful to just try and work through a simplified example, so
(x+1)(y+1)(z+1) = 2*3*5
how many ways would there be, whereas if its
(x+1)(y+1)(z+1) = 2^2*3*5
how many ways?

If there is a specific part youre unsure about, its best to be as clear as possible.
(edited 1 year ago)

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