Stefan Ram <ram@zedat.fu-berlin.de> wrote:
+---------------
|   Recently a question was posed in TV about the number of "5"
|   characters occuring within all integral decimal numerals
|   between 0 and 100.
|  
|   Frank Buss suggested the following source code to
|   calculate the result in Lisp:
...
|   I wrote this in Perl:
+---------------

Actually, I don't like *any* of the (many) solutions presented!  ;-}
This is a problem you should be doing in your head! QUICK! What's
the answer for 0-9? One, of course. And the answer for 0-99? One
for each decade, plus 10 for the 50's, or 20 [as many responded].
What about 0-999? 300. 0-9999? 4000.  And 0-99999? 50000, duh!
Got the pattern yet...?  ;-}

There's some ancient aphorism about this, something about *thinking*
first, before haring off to write code. But, hey, Gauss got in a lot
of trouble for thinking [Google for "Gauss sum class"], so I suppose
nobody does that any more.

This one is only slightly harder: Among the printed representations
of integers from 0 to (expt 10 n), how many contain *at least one* "5"?
Hint: ((1 . 1) (2 . 19) (3 . 271) ... )


-Rob

-----
Rob Warnock			<rpw3@rpw3.org>
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