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 ''even'', the '''sum''' must be divisible by '''11''', and |
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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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::<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) |
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===30 mins not 30 years=== |
===30 mins not 30 years=== |
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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. |
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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