Talk:Rare numbers

comments concerning interesting observations from an webpage

(The author's webpage, the last URL reference from this task's preamble, re-shown below:)

(a URL reference):

•   author's  website:   rare numbers   by Shyam Sunder Gupta.     (lots of hints and some observations).

I was considering adding checks   (to the REXX program)   to assert that for:

•   when the number of digits in a rare number is even,   the   sum   must be divisible by   11,     and
•   when the number of digits in a rare number is   odd,   the   difference   must be divisible by   9.

In fact, all the other (previous) checks   (in the REXX program)   have already filtered out all the (above) wrong cases,   so the above two   interesting observations   are never observed to be false,   so the checks are (at that point) in fact, redundant.

In fact, the webpage section contains a errors,   the difference   must be divisible by   9,   not   11   as it states in the text.

Also, the mention of   A²   and   B²   having to be divisible by some number seems to be also wrong.   I'm attempting to contact the author via e-mail.     -- Gerard Schildberger (talk) 20:59, 8 September 2019 (UTC)