Some spreadsheet ideas

Magic grid. Try this trick. Copy out the grid below. Now put a circle round any number and cross out all the others in the same row and column. Choose another number that has not been crossed out, circle it and once again cross out all the others in the same row and column. Continue until all the numbers are used up. Add up the four numbers you circled. Do you get 30? How does this work? Use a spreadsheet to create more, and bigger, magic grids.

Chaos. If you choose a value for the constant c and an initial value for the variable x, then the following formula will tell you how to work out the next value of x:

	next value = cx(1-x)

This formula can be used over and over again, to obtain a sequence of numbers. Start with 5 for c and about 0.1 for x and see what you get.

Spreadsheet

You can find a brief introduction to the basics of spreadsheeting - using ClarisWorks - at Swarthmore. Spreadsheets in Education contains a varied collection of starting points, including lists of links.
Java is a programming language that browsers like Netscape can understand. For an illustration of the java language as applied to spreadsheets, visit the site at Sun, but note you must be using the 32-bit version of Netscape to do this. Another java spreadsheet can be found at Robert's online spreadsheet. Try the home page of The Spreadsheet User journal.

There are many other web resources based on Excel.