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Hey Guys!

I'm in a really emergency situation, please help.

The question is: What's the N sentence in this:

\(5,55,555,...\)

You know, it continous with this pattern, but what if we want to find 1000th sentence?

PLEASE HELP!

Guest Oct 15, 2017
 #1
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Wouldn't 1,000th sentence consist of 1,000 5s?. Or 555555555555.........1,000 of them? And what do you want done with the sequence? Add them all up? 5+55+555+5555........to 1000 5s?.

Guest Oct 15, 2017
 #2
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\(F(n) = \sum_{i=1}^n 0.5*10^i\)

 

This would be the n'th term in this sentence if I understood your question correctly. You can input n=1,n=2 to get the first and second term. By putting in n=1000 you will get your desired answer. I'm not going to type out a thousand 5's but hopefully you get the idea of why this works. 

Quazars  Oct 15, 2017
 #3
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Thanks. I've got my answer.

I have absolutely "Nothing" to do with this. Actually, my education system is not very practical. this is a sample question from a sample test that a 9th-grade math teacher said. All of his questions are really hard to solve.

Thank you again.

P.S: Sorry for my bad English.

Guest Oct 15, 2017
edited by Guest  Oct 15, 2017

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