Kaprekars Constant
Kaprekar's constant
The number 6174 is known as Kaprekar's constant[| Kaprekar's Constant 6174] 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.⁋.⪪.⋰;
kp:=k.⋱.⚯*1 -k.⋰.⚯;
_y=k;
var r=-1, rt=-1,rs=[];
try
{
(1..8)@(
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.⁋.⪪;
if(i==8)
{
⊫(i,"FAILEDFORNUMBER",x)
}
}
);
}
catch(err)
{
// ⊫(err,"ERROR")
}
//⊫([x,r,rt,rs])
//return([x,r,_y,rs])
return([x,r,rs])
}
| x | kc | |||||||||
| 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 |
|