Reducing a 4 digits numbers to a 2 digits number ?Prev TopicNext Topic

• frenchie

  

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  Nov 7, 2024, 5:02 pm

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  Hi everyone,

  I don't think that is possible but I'm gone ask anyway.

  How can you reduce a 4-digit number into a 2-digit number using every possible method, while also ensuring that you can trace back to the original 4-digit number? List all possible ways to do this, such that the transformation is reversible and allows recovery of the original number.

  I forgot to mention that I work on Excel 2007.

  Thank you.

  Frenchie.
• hypersoniq

  

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  Nov 9, 2024, 7:12 pm

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  There are 10,000 combinations of 4 digit numbers ( 0000 to 9999 ), but only 100 combinations of 2 digits ( 00 to 99 ).

  The best you could hope for is a 1 to 100 mapping, such that 00 would represent the group of 0000 to 0100 through 99 representing 9899 to 9999. There is not enough info in 2 digits to reconstruct the 4 digit number.

  Have an EXCELlent day!
• frenchie

  

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  Nov 12, 2024, 3:24 pm

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  Thank you hypersoniq.

  Frenchie.
• ddude003

  

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  Nov 13, 2024, 4:38 pm

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  Are you thinking about a CRC or Hashing algorithm?
• frenchie

  

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  Nov 14, 2024, 5:36 pm

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  What ever would give me what I ask in post 1.

  Frenchie.
• hypersoniq

  

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  Nov 14, 2024, 7:42 pm

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  Putting it another way, you need to represent 10000 4 digit numbers. With only digits your max is 10×10, 100 possibilities. If you were to expand the 2 digit encoding, you would need 100 unique characters. 100x100 is the 10,000... if you were to include digits, and all 26 upper case letters, and all 26 lower case letters that is closer... 62 x 62 = 3844... you would need to add 38 more characters to that list to get all 10,000 pick 4 combos encoded into 2 characters. Perhaps adding punctuation and Greek characters can get you to 100. Unicode.

  Have an EXCELlent day!
• frenchie

  

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  Nov 16, 2024, 2:21 pm

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  Thanks hypersoniq, I need to change my lottery system from using this 4 digits number some how, I like your idea

  of letters but it would still required to find witch letter witch would also required a selection, I tried to use Digital root,

  binary number etc... but still stuck, Thank you tho for your input, really appreciate it.

  Frenchie.
• frenchie

  

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  Nov 17, 2024, 1:26 pm

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  I really missed Craig aka RL-RANDOMLOGIC, Steve  winsumloosesum and Willy notmyday those guys were always full of answers,

  and ready to work on the issue and solve it, but there are not here anymore I really enjoyed that time, maybe Craig could have created

  a small program to solve this one if it could be solve ?

  Frenchie.
• ddude003

  

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  Nov 18, 2024, 2:36 pm

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  So, you not only what us to give you the basic idea or point you to the name of a method, you want us to solve the problem, write the code and give you the code too?

  You buy them the books and send them to school and what do they do?

  Maybe you could ask ChatGTP for that...
• frenchie

  

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  Nov 23, 2024, 2:58 pm

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  Hi ddule003, I feel some angriness !!  " So, you not only what us to give you the basic idea or point you to the name

  of a method, you want us to solve the problem, write the code and give you the code too? "isn't that that purpose of

  asking a question ? tell me if I'm wrong ? Thank you.

  Frenchie.
• ddude003

  

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  Nov 24, 2024, 9:23 pm

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  Asked and answered...
• thamizhpayan

  

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  Nov 25, 2024, 9:01 am

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  Short sum

  Root sum

   

  are two ways to take the sum of 4 digit number and calculate.

  With root sum, We get good even spread. It is 0-9 which means it's one digit and not two digit.

   

  All of these help to deal with smaller set when analyzing but when expanded lead to more combinations to play.

   

  Good luck
• frenchie

  

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  Nov 29, 2024, 2:08 am

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  Thanks thamizhpayan, but these won't solve my problem, I'm dealing with numbers between 1000 and 7561 so a total of 6561

  numbers. I would like to reduce some how with some algorithm, code or formula and when using it backward I could return to

  the original number, it might be impossible but I just give it a try just in case that in this Lottery Post site that I really like, are

  some people way smarter than me in complex calculations, so maybe I though I would get lucky.

  Frenchie.
• cottoneyedjoe

  

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  Dec 2, 2024, 2:34 pm

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  In response to frenchie

  Quote: Originally posted by frenchie on Nov 7, 2024

  Hi everyone,

  I don't think that is possible but I'm gone ask anyway.

  How can you reduce a 4-digit number into a 2-digit number using every possible method, while also ensuring that you can trace back to the original 4-digit number? List all possible ways to do this, such that the transformation is reversible and allows recovery of the original number.

  I forgot to mention that I work on Excel 2007.

  Thank you.

  "reduce a 4-digit number into a 2-digit number using every possible method, while also ensuring that you can trace back to the original 4-digit number"

  This is not possible. If you have a set of size 10000 and you map every element of that set onto a different set of size 100, some elements in the original set will have to map on to the the same element in the new set. If you then take an arbitrary element from the smaller set and ask, "What mapped on to this?" the answer will not necessarily be a single element from the original set, but instead a subset of the original set. In other words, the reverse mapping is not what mathematicians call "well-defined."
• frenchie

  

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  Dec 4, 2024, 2:37 pm

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  Thank you cottoneyedjoe.

  Frenchie.