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10 replies to this topic

#1 K Sengupta

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Posted 30 October 2009 - 11:21 PM

F(x) denotes the absolute difference between SOD(x) and SOD(x+2), whenever x is a positive integer.

Determine the total number of distinct values of F(x) < 2000.

Note: SOD(x) denotes the sum of digits in the base ten representation of x.

Edited by K Sengupta, 30 October 2009 - 11:21 PM.

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#2 3ala2

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Posted 31 October 2009 - 06:25 AM

Spoiler for i think

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#3 adee

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Posted 31 October 2009 - 09:42 AM

@3ala2, there are more values of F(x)
Spoiler for

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#4 3ala2

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Posted 31 October 2009 - 12:46 PM

@3ala2, there are more values of F(x)

Spoiler for


mm.. i agree with ur method..

Spoiler for but i think ur answer is wrong

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#5 Tuckleton

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Posted 31 October 2009 - 01:45 PM

I am so lost. Could someone please give me a quick example of F(x) in action and how it does, or does not, fit into the solution we are supposed to look for. Thanks!
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#6 plainglazed

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Posted 31 October 2009 - 02:05 PM

Spoiler for Tuck

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#7 adee

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Posted 31 October 2009 - 10:24 PM

mm.. i agree with ur method..

Spoiler for but i think ur answer is wrong


Yaa... I thought F(x)should be less than 1000 :duh: ... thanks for verifying ^_^
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#8 xamdam

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Posted 31 October 2009 - 10:36 PM

Fun puzzle. Where do you get so many puzzles, K Sengupta?

Edited by xamdam, 31 October 2009 - 10:40 PM.

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#9 jerbil

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Posted 01 November 2009 - 12:12 AM

Fun puzzle. Where do you get so many puzzles, K Sengupta?


I was going to ask him that, xamdam. Maybe KS is a reincarnation of Ramanujan :)
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#10 K Sengupta

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Posted 01 November 2009 - 03:45 PM

Fun puzzle. Where do you get so many puzzles, K Sengupta?


None of the said puzzles contributed to this site is an original.

The various sources wherefrom these problems are gleaned happens to be so numerous that I have since stopped countin' 'em.

Edited by K Sengupta, 01 November 2009 - 03:46 PM.

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