# What's New -  October 2002

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October 30, 2002:   Here's today's problem and the Expressions 2002 program that solves it:

Insert +(addition) and × (multiplication) operators as required into the string of digits 123456789 to form an expression that evaluates to 2002.  For example, if the desired value were 100,  then one  solution would be 12+34+5×6+7+8+9=100.

This program was prompted by a viewer request.    It is similar to the Expressions100 program which required  + and - operators.   The complication this time is that multiplications must be performed before additions.   The same viewer also posed a much tougher version that's providing more hours of fun - stay tuned.

October 26, 2002:

A little exercise in Computational Geometry was posted in the Delphi Techniques section the other day.   Included are an improved function testing  for line intersection,  and functions to construct a perpendicular from a point to a line and to construct a line through a point on a line at a given angle.    I developed them for use in  Dudeney's Dissection program,  but it seems like they may be handy for any problems which combine computer programming and geometry.

October 20, 2002:  Here's a little program that lists the largest files on a user selected drive.  I just discovered and deleted 30 mb of disk space in Outlook Express mailbox files left over from a conversion to Outlook several months ago.  Now if I can just figure where that other gigabyte or so of hard drive bloat came from.     List Large Files is available for downloading from a new Utilities programs section

October 17, 2002:   One more Dudeney gem before we move on.   100 years ago, puzzleist H. E. Dudeney came up with a way to dissect a square into 4 polygons which can be reassembled to form an equilateral triangle.     Dudeney's Dissection lets you print outlines or partially solved solutions to work on for yourself.

My first attempt,  shown here,  is not quite up to the job - the triangle formed is isosceles, but not equilateral.   The real solution is not  quite so symmetrical.

Guess I'd better go get all these paper clippings cleaned up before somebody comes along and delivers more comments about acting my age.

October 8: 2002:   Here's another little program which solves a puzzle from English recreational mathematician and puzzlist Henry  Ernest  Dudeney.  Find all sets of four digits, [a,b,c,d],  which when formed  into two numbers,  (a, bcd or ab,  cd), have the property that the product contains the same four digits.   I  copied Dudeney's naming and called this program Pierrot's Puzzle.  If you know who or what a Pierrot is,  you are probably either European or into theater.

October 4, 2002:  DFF Newsletter #29 was sent today.

Word of the month - Samhainophobia: the fear of Halloween.   Nothing to do with Delphi, I was just looking up things to entertain the grandkids and ran across the word.  It  seems like one everyone should use at least once in October.  If you really get into it, you can also impress your friends by working these into conversations his month:

• wiccaphobia  (fear of witches )

• nyctophobia  (the dark)

• coimetrophobia (cemeteries)

• ailurophobia (cats)  - not to be confused with aulophobia - the fear of flutes.  Really!

• phasmophobia (ghosts)

• arachnophobia  (spiders)

October 3, 2002:  I've been trying to send a newsletter for the past day but the list server at M6.net  (my  DFF host site) is not working.  They say it should be fixed in a couple of days.     Today it appears that email for delphiforfun.org is broken also.    So if you have sent an email that got returned or sent feedback requesting contact and haven't  heard from me,   try it again in a day or so.

October 2, 2002:   I wrote a little program today that analyzes DelphiForFun log files and extracts program download statistics.   Here's a page of 'Top 25 Program Downloads " for the past 11 months, 30 days and 7 days.     There's still some work to do automate generation of the tables but the numbers are kind of interesting.

October 1, 2002:

The  Chessboard Fallacy program  tells you how to cut a chessboard and rearrange the pieces in such a way that the number of squares is reduced from 64 to 63.   Unlike some cutting puzzles, these pieces do not cheat on the angles - the pieces will fit exactly.   Of course there are many  ways to cheat....