Talk:Rare numbers: Difference between revisions
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::* when the number of digits in a rare number is ''odd'', the '''difference''' must be divisible by '''9'''. |
::* when the number of digits in a rare number is ''odd'', the '''difference''' must be divisible by '''9'''. |
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In fact, all the other (previous) checks (in the REXX program) have already filtered out |
In fact, all the other (previous) checks (in the REXX program) have already filtered out the two (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. |
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In fact, the webpage section contains a errors, the '''difference''' must be divisible by '''9''', not '''11''' as it states in the text. |
In fact, the webpage section contains a errors, the '''difference''' must be divisible by '''9''', not '''11''' as it states in the text. |
Revision as of 21:02, 8 September 2019
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 the two (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)