Efficient Sum Evaluation: Tips for Solving 100 P i Permutations

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Discussion Overview

The discussion revolves around evaluating the sum of permutations, specifically the expression "100 P i" where i varies from 1 to 100. Participants seek clarification on the meaning of the notation and the nature of the sum being evaluated.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Homework-related

Main Points Raised

  • One participant requests help with evaluating the sum of "100 P i".
  • Another participant questions the meaning of "100 P i" and whether "P" is a constant.
  • Several participants clarify that "100 P i" refers to the number of permutations of i objects selected from 100, expressed as 100!/(100-i)!, but they seek to understand what is being summed.
  • One participant proposes a potential interpretation of the sum as \sum_{i=0}^n{}_{100}P_i and asks if they are correct.
  • The original poster confirms that this interpretation is accurate and inquires about explicit methods for calculating the sum for arbitrary n.

Areas of Agreement / Disagreement

Participants generally agree on the interpretation of "100 P i" as permutations, but the specifics of the sum and methods for evaluation remain unresolved.

Contextual Notes

There are limitations in the discussion regarding the clarity of the original sum's definition and the assumptions about the variable n.

JasonJo
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i need help evaluating this sum:

(that is 100 P i, or the permutation)
 
Last edited:
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What does "100 P i" mean with i going from 1 to 100? Is P a constant?
 
I can't see your attatchment. Does 100 P i mean the number of permuations of i objects selected from 100? namely, 100 P i= 100!/(100-i)!

What's being summed?
 
shmoe said:
I can't see your attatchment. Does 100 P i mean the number of permuations of i objects selected from 100? namely, 100 P i= 100!/(100-i)!

What's being summed?

yeah I'm sorry if it came out bad, but yeah it's the permutation
 
So what's being summed then?
 
I'm going to take a stab in the dark and guess you mean

[tex]\sum_{i=0}^n{}_{100}P_i[/tex]

Am I close?
 
yeap, that's exactly it. is there any explicit way to calculate the sum for arbitrary n?
 

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