Number theory involving sum of digits of a number:












-2












$begingroup$


Let a fixed natural number m be given Call a positive integer n to be a GRT number iff:




  1. $n equiv 1 pmod m$


  2. Sum of digits in decimal representation of $n^2$ is greater than or equal to sum of digits in decimal representation of $n$.



How many GRT numbers are there ?










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  • 4




    $begingroup$
    Please fix the question and please never type something like $2. Sum of digits in decimal representation of n^2 is greater than or equal to sum of digits in decimal representation of n.$ again.
    $endgroup$
    – dan_fulea
    Feb 1 at 17:34
















-2












$begingroup$


Let a fixed natural number m be given Call a positive integer n to be a GRT number iff:




  1. $n equiv 1 pmod m$


  2. Sum of digits in decimal representation of $n^2$ is greater than or equal to sum of digits in decimal representation of $n$.



How many GRT numbers are there ?










share|cite|improve this question











$endgroup$








  • 4




    $begingroup$
    Please fix the question and please never type something like $2. Sum of digits in decimal representation of n^2 is greater than or equal to sum of digits in decimal representation of n.$ again.
    $endgroup$
    – dan_fulea
    Feb 1 at 17:34














-2












-2








-2





$begingroup$


Let a fixed natural number m be given Call a positive integer n to be a GRT number iff:




  1. $n equiv 1 pmod m$


  2. Sum of digits in decimal representation of $n^2$ is greater than or equal to sum of digits in decimal representation of $n$.



How many GRT numbers are there ?










share|cite|improve this question











$endgroup$




Let a fixed natural number m be given Call a positive integer n to be a GRT number iff:




  1. $n equiv 1 pmod m$


  2. Sum of digits in decimal representation of $n^2$ is greater than or equal to sum of digits in decimal representation of $n$.



How many GRT numbers are there ?







elementary-number-theory






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edited Feb 1 at 17:56









Arturo Magidin

266k34591921




266k34591921










asked Feb 1 at 17:30









Mayank MishraMayank Mishra

605




605








  • 4




    $begingroup$
    Please fix the question and please never type something like $2. Sum of digits in decimal representation of n^2 is greater than or equal to sum of digits in decimal representation of n.$ again.
    $endgroup$
    – dan_fulea
    Feb 1 at 17:34














  • 4




    $begingroup$
    Please fix the question and please never type something like $2. Sum of digits in decimal representation of n^2 is greater than or equal to sum of digits in decimal representation of n.$ again.
    $endgroup$
    – dan_fulea
    Feb 1 at 17:34








4




4




$begingroup$
Please fix the question and please never type something like $2. Sum of digits in decimal representation of n^2 is greater than or equal to sum of digits in decimal representation of n.$ again.
$endgroup$
– dan_fulea
Feb 1 at 17:34




$begingroup$
Please fix the question and please never type something like $2. Sum of digits in decimal representation of n^2 is greater than or equal to sum of digits in decimal representation of n.$ again.
$endgroup$
– dan_fulea
Feb 1 at 17:34










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I can't prove it absolutely, but for any $m$ there must be infinitely many. Any large $n$ that is $equiv 1 bmod m$ will have a square with lots more digits than $n$ has, so the sum of digits of the square will be larger.






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    $begingroup$

    I can't prove it absolutely, but for any $m$ there must be infinitely many. Any large $n$ that is $equiv 1 bmod m$ will have a square with lots more digits than $n$ has, so the sum of digits of the square will be larger.






    share|cite|improve this answer









    $endgroup$


















      1












      $begingroup$

      I can't prove it absolutely, but for any $m$ there must be infinitely many. Any large $n$ that is $equiv 1 bmod m$ will have a square with lots more digits than $n$ has, so the sum of digits of the square will be larger.






      share|cite|improve this answer









      $endgroup$
















        1












        1








        1





        $begingroup$

        I can't prove it absolutely, but for any $m$ there must be infinitely many. Any large $n$ that is $equiv 1 bmod m$ will have a square with lots more digits than $n$ has, so the sum of digits of the square will be larger.






        share|cite|improve this answer









        $endgroup$



        I can't prove it absolutely, but for any $m$ there must be infinitely many. Any large $n$ that is $equiv 1 bmod m$ will have a square with lots more digits than $n$ has, so the sum of digits of the square will be larger.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Feb 1 at 18:06









        Ross MillikanRoss Millikan

        301k24200375




        301k24200375






























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