16 January 2008
===============

Here's the plan:


A non-interactive version is described at http://nrich.maths.org/
public/viewer.php?obj_id=5468.

The idea for an interactivity is simpler than what's described there
- we don't want to get into 2 player stuff.

So you make a 10 by 10 square and fill it with numbers 1-100. The
controls would be something like:
         Restart
         Click on an uncoloured number
                 machine checks that it's a factor or multiple of previous
number
clicked.
                 Factors get coloured one way, multiples another.
                 Other numbers generate an error "Not a factor or multiple" and
remain uncoloured
                 Good numbers are added to a growing list displayed somewhere.
                          (or drawn on the grid by chaining numbers with
arrows)
                 There's a list length count display.

One interesting goal with this is "What's the longest chain you can
make?", but there will be other uses too like the two player thing.

Would it be OK to work on this instead of the bridge problem for a bit.

25 January 2008
===============

Thought I'd lost it! But now it's recovered. Zip it up and stick it on the site.

27 January 2009
===============

Updated. Added an undo button. God willing, I will never have to interfere with this thing again!