Challenge #426: Perfect Numbers

[fdavy]

Here's my answer

[RashedDS]

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[TobiasFitschen]

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 After I was done, I suspected that this is not the most efficient way, but got to learn something after checking out how others approached the challenge.

[ed_hayter]

'Perfect' one to come back to post bank holiday

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[shancmiralles]

First time to participate 💞

Have to search further on formulas .. you really have to know your formulas ( or be really friends with Google 😆 ) 

 

[JeffF]

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[shancmiralles]

** on my 2nd solution i have 2 filter tools just to separate the "[RowCount] < [Num] " and "Mod([Num], [RowCount]) = 0" formulas

[Pilsner]

My Solution:

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[Carolyn]

I solved this 2 different ways

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For the first way, I generated every integrate from 1 to the number, saw if the number was evenly divisible by that number, and summarized. Easy but slow. 


For the second way, I knew that I only needed to test up to the square root of the number, rounded down. For example, if I was evaluating 99, I only need to test through 9. Any other integrates that will divide into 99 would be caught with the numbers less than 99. 9 goes into 99 so it would catch when I evaluate through 9. Then I just need to find its buddy which is 11. If I test all the way through 99, I'll catch the buddy 11 that way, but it's doing more evaluation than I really need to.

It added a number of extra Tools to make that work, but it ran faster and satisfied my inner mathematician, so I'm calling it a win

 

[RyanWade]

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