Can you find the smallest positive number such that if you shuffle the digits of the number in a particular order, the shuffled number becomes twice the original number.
Source: http://gpuzzles.com/mind-teasers/very-hard-maths-riddle/
I understand the answer is $125874 => 251748$
$251748$ is twice the $125874$ and have same digits $1,2,4,5,7$ & $8$
but how to solve this non programmatic ?
I have a detailed solution to this problem written up on the math.SE blog.