This puzzle requires that you enter
the digits 1 through 8 in the circles and squares (one digit in
each figure) so that the number in each square is equal to the
sum on the numbers in the circles which adjoin
Background & Techniques
I ran across this little puzzle in a book that was one of
my Christmas gifts this year:
Giant Book of Mensa Mind Challenges ,
Stirling Publications, 2003. There are eight versions of
the single unique solution (rotate it 90° three times, flip it
over or view it in a mirror and rotate it three more
The solution is not included as part of the program but if
you really get stuck, it is available as a sample problem with
our Brute Force problem
solver which uses exhaustive search to find solutions for a
given set of equations and values.
Non-programmers are welcome to read on,
but may want to skip to the bottom of this
page to download executable version of the program.
Notes for programmers:
I used automatic drag and drop to allow users to drag the 8 TLabel
controls (captioned 1 though 8) to the 8 TShape
controls, four circles and four squares. I assigned
the labels and shapes to arrays in order to simplify the
code. The Tag property was used assign a
numeric value to a shape when a label was dropped on it.
Only a few tricky things, like remember to reset the shape's tag
property to zero if a label is dragged from one shape to
another. Also if the receiving shape is already occupied
(its Tag is >0), move the corresponding label back to its
home starting position.
I think everything else is pretty much self explanatory.
Running/Exploring the Program