Difference between revisions of "Kaprekars Constant"
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Revision as of 21:28, 1 September 2024
Kaprekar's constant
The number 6174 is known as Kaprekar's constant[1][2][3] after the Indian mathematician D. R. Kaprekar. This number is renowned for the following rule:
Take any four-digit number, using at least two different digits (leading zeros are allowed). Arrange the digits in descending and then in ascending order to get two four-digit numbers, adding leading zeros if necessary. Subtract the smaller number from the bigger number. Go back to step 2 and repeat.
Video: https://www.youtube.com/watch?v=xtyNuOikdE4
z^3 Solution
1001..1010@kc; function kc(x) { k=((x⁋)#).sort(); kp:=((k⋱)⚯*1 -(k⋰)⚯); _y=k; var r=-1; var rt=-1; var rs=[]; try { (1..7)@( function(i) { var t=kp(_y) if(t==6174 && r==-1) { r=i; rt=t; rs.push(t); throw("EXIT") } else { rs.push(t) } _y=((t⁋)#); //⊫("AFTER",i,_y); } ); } catch(err) { } ⊫([x,r,rt,rs]) return([x,r,_y,rs]) }
Answer:
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1001 |
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1002 |
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1003 |
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1004 |
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1005 |
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1006 |
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1007 |
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1008 |
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1009 |
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1010 |
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