### I hate mathematics

Via Gary King, I found this little weirdness, called the 6174 problem.

- Pick any four distinct digits (e.g., 6, 2, 9, 0)
- arrange them into the largest possible integer (e.g., 9620)
- arrange them into the smallest (e.g., 0269)
- subtract the smaller from the larger (e.g., (- 9620 0269) => 9351)
- go back to step 2 and repeat

Apparently that's the longest one, I haven't bothered to check myself but I did translate Gary's Lisp code to Python. I took the memoize implementation straight from the Python Decorator Library. The whole thing is about 100 lines (which includes doctests).`9620 - 0269 = 9351`

9531 - 1359 = 8172

8721 - 1278 = 7443

7443 - 3447 = 3996

9963 - 3699 = 6264

6642 - 2466 = 4176`7641 - 1467 = 6174`

`7641 - 1467 = 6174`

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## 1 kommentar:

david copperfield did this trick on TV back in the 90's. it is a pretty neat trick for kids and makes them go WOW.

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