Date: 24/05/2020 11:51:45
From: Spiny Norman
ID: 1560943
Subject: 6174 is also known as Kaprekar's Constant

How delightfully odd

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Date: 24/05/2020 11:58:25
From: transition
ID: 1560944
Subject: re: 6174 is also known as Kaprekar's Constant

Spiny Norman said:


How delightfully odd

watched that, quite good

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Date: 24/05/2020 12:02:13
From: The Rev Dodgson
ID: 1560946
Subject: re: 6174 is also known as Kaprekar's Constant

Clearly the true value of pi is really 3.174, and this constant is just (pi +3)×1000.

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Date: 24/05/2020 12:05:13
From: party_pants
ID: 1560947
Subject: re: 6174 is also known as Kaprekar's Constant

6174 = Golden Bay, Western Australia.

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Date: 24/05/2020 12:08:19
From: Peak Warming Man
ID: 1560948
Subject: re: 6174 is also known as Kaprekar's Constant

party_pants said:


6174 = Golden Bay, Western Australia.

Getting odder and odder.

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Date: 24/05/2020 12:11:34
From: dv
ID: 1560949
Subject: re: 6174 is also known as Kaprekar's Constant

Interesting. WP gives 495 has the 3 digit equivalent.

There appears to be no corresponding 2 digit equivalent: performing this algorithm just results in cyclical behaviour.

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Date: 24/05/2020 12:20:11
From: SCIENCE
ID: 1560950
Subject: re: 6174 is also known as Kaprekar's Constant

In base 10, it can easily be shown that all numbers of the form 6174, 631764, 63317664, 6…333…17…666…4 (where the length of the “3” sequence and the length of the “6” sequence are the same) are fixed points of the Kaprekar mapping.

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Date: 24/05/2020 12:21:04
From: Spiny Norman
ID: 1560951
Subject: re: 6174 is also known as Kaprekar's Constant

The Rev Dodgson said:


Clearly the true value of pi is really 3.174, and this constant is just (pi +3)×1000.

No, pi is unarguably 4. :D

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Date: 24/05/2020 12:41:55
From: The Rev Dodgson
ID: 1560959
Subject: re: 6174 is also known as Kaprekar's Constant

Spiny Norman said:


The Rev Dodgson said:

Clearly the true value of pi is really 3.174, and this constant is just (pi +3)×1000.

No, pi is unarguably 4. :D

Good point.

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Date: 24/05/2020 12:44:10
From: The Rev Dodgson
ID: 1560960
Subject: re: 6174 is also known as Kaprekar's Constant

The Rev Dodgson said:


Spiny Norman said:

The Rev Dodgson said:

Clearly the true value of pi is really 3.174, and this constant is just (pi +3)×1000.

No, pi is unarguably 4. :D

Good point.

Although I don’t know where the pi = 4! comes from.

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Date: 24/05/2020 12:49:41
From: SCIENCE
ID: 1560965
Subject: re: 6174 is also known as Kaprekar's Constant

The Rev Dodgson said:


The Rev Dodgson said:

Spiny Norman said:

No, pi is unarguably 4. :D

Good point.

Although I don’t know where the pi = 4! comes from.

Manhattan

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Date: 25/05/2020 00:12:59
From: wookiemeister
ID: 1561179
Subject: re: 6174 is also known as Kaprekar's Constant

This works if the perimeter is infinity I guess

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Date: 25/05/2020 00:18:13
From: sibeen
ID: 1561180
Subject: re: 6174 is also known as Kaprekar's Constant

wookiemeister said:


This works if the perimeter is infinity I guess

It works because it never becomes a circle.

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Date: 25/05/2020 00:21:14
From: wookiemeister
ID: 1561181
Subject: re: 6174 is also known as Kaprekar's Constant

sibeen said:


wookiemeister said:

This works if the perimeter is infinity I guess

It works because it never becomes a circle.


The way i see it is because infinity isn’t exactly a number

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Date: 25/05/2020 00:33:36
From: wookiemeister
ID: 1561182
Subject: re: 6174 is also known as Kaprekar's Constant

You could go the other way perhaps ?

Dunno

No pencil

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Date: 25/05/2020 00:35:25
From: sibeen
ID: 1561183
Subject: re: 6174 is also known as Kaprekar's Constant

wookiemeister said:


You could go the other way perhaps ?

Dunno

No pencil

Nup. expand a circle and you get a circle.

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Date: 25/05/2020 03:46:39
From: mollwollfumble
ID: 1561189
Subject: re: 6174 is also known as Kaprekar's Constant

transition said:


Spiny Norman said:

How delightfully odd

watched that, quite good

OK, I get it.

Looks like 6174 is the only four digit number (other than all digits equal) that satisfies the recurrence relation: digits in descending order minus digits in ascending order equals original number. And many other 4 digit numbers are attracted to it.

The attraction is quite strong. The many to one can be seen from: 9876 – 6789 = 4321 – 1234 = 3087. That means that in this case 144 different initial numbers are attracted to the answer 3087 as the second step. It doesn’t take too many powers of 144 to exceed 9999.

8730 – 0378 = 7992. 9972 – 2779 = 7173. 7731 – 1377 = 6354, 6543 – 3456 = 3087.

Hey, it doesn’t work. We’ve got a loop here, not an attraction to 6174.

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Date: 25/05/2020 07:39:28
From: btm
ID: 1561192
Subject: re: 6174 is also known as Kaprekar's Constant

mollwollfumble said:


transition said:

Spiny Norman said:

How delightfully odd

watched that, quite good

OK, I get it.

Looks like 6174 is the only four digit number (other than all digits equal) that satisfies the recurrence relation: digits in descending order minus digits in ascending order equals original number. And many other 4 digit numbers are attracted to it.

The attraction is quite strong. The many to one can be seen from: 9876 – 6789 = 4321 – 1234 = 3087. That means that in this case 144 different initial numbers are attracted to the answer 3087 as the second step. It doesn’t take too many powers of 144 to exceed 9999.

8730 – 0378 = 7992. 9972 – 2779 = 7173. 7731 – 1377 = 6354, 6543 – 3456 = 3087.

Hey, it doesn’t work. We’ve got a loop here, not an attraction to 6174.

9972 – 2779 ≠ 7173, although the correct 9972 – 2799 = 7173. Also, 8730 – 0378 = 8532; 8532 – 2358 = 6174.

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