LuckyDucky

(1/1*2)+(1/2*3)+(1/3*4)+(1/4*5)+ .............+(1/99*100) =

= [1/1 - 1/2] + [1/2 - 1/3] + [1/3 - 1/4] + ... + [1/98 - 1/99] + [1/99 - 1/100] = 1/1 - 1/100 = 99/100 

:D

Some people just give a link and expect us to do it and they do not learn they just are answer hungry. 

I'm sorry I can't help then

What is the direct issue you are facing

for example do you not understand the topic or is it a formula problem?

Instead of posting a link please ask what the problem you are facing is?

Please don't repost "guest"

Please do not post AOPs Alcumus questions.

HERE IS A VERY HELPFUL LINKING REGARDING YOUR QUESTION 

https://artofproblemsolving.com/wiki/index.php/Distinguishability

Please, everyone, take a look at the link it has helped me so much in my AOPs coursework.

Oh oops I did not see that imma try it agian

j+4=-17

j=-17+4

j=-13

CPhill Is that correct?

While I definitely agree with Humomimihu it is important to show all your steps and if possible not give the final answer. Furthermore, if the same person asked a similar question again Don't answer it because you already showed them how to do it. 

HELP DON'T CHEAT!!!!!

:D