PASCAL’S TRIANGLE:
An interactive version of Pascal’s Triangle.
http://mathforum.org/dr.cgi/pascal.cgi
Here is another site on Pascal’s triangle:
http://mathforum.org/web.comments/ladja.pascal.html
PROBLEM SOLVING:
This site give a nice introduction to problem-solving.
http://mathfocus.tripod.com/page3.html
A site which lists other sites on mathematical puzzles:
https://www.mynhusd.org/