Talk:Rare numbers: Difference between revisions
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::* 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'''.
::<br><br>n-r is divisible by 9 for all Rare numbers. n-r is also divisible by 99 when the number of digits is odd. (see [[Talk:Rare_numbers#30_mins_not_30_years]])--[[User:Nigel Galloway|Nigel Galloway]] ([[User talk:Nigel Galloway|talk]]) 13:48, 21 September 2019 (UTC)
===30 mins not 30 years===
If Shyam Sunder Gupta has really spent 30 years on this he should have stayed in bed. Let me spend 30mins on it. The following took 9mins so any questions and I have 21mins to spare.
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