Супер!

nice radix conversion from int to string

counting matches of '1' is simple, and could easily scale to higher radixes such as octal
could easily be extended to match multiple digits, such as .count('137')

range traversal is clear

accumulator function sum() over a list is also a nice aggregate function

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What a clever way to solve this problem. I wish I could've solve math problems like this earlier on.

I think its pretty readble to me.

This is awesome!

When you know the math theory behind it!

Stop writing one line! It is not readable

well, most of times we call some functions without knowing how it's done inside the blackbox, that is abstraction. it is a fact that is not readable but you would not need to read that.

Hi guys

please what I need to do and improve in to come up with solution like these ?
thanks

What I need to learn and improve in to come up with solutions like these??

Meanwhile, please remember to put a spoiler tag on your comments if they contain code or a discussion of the solution methods, thanks. I have put the flag on your comment already.