The Java Applet

The IntegerZone is a Java applet (written years ago), which I wrote with the intention of allowing users to "explore" the integers and integer operations.

(There may be a delay while Java starts and the applet (~130k) downloads. If you can't see any button at all, you may not have the Java plugin installed, or Java may have been disabled in the browser).

How it works

The integers are displayed in a simple rectangular grid. The grid can be scrolled up and down and resized. The user chooses a mode, and this defines their interaction with the integers. Some of the modes are for exploration, others help the user test their knowledge and calculation skills.

Topics Currently Included

• Arithmetic: addition, subtraction, multiplication and division.
• Factorization: explore and test.
• Highest common factors and lowest common multiples. Using the Euclidean algorithm to find HCF's.
• Multiples of a number: explore and test.
• Tables Tests: addition, subtraction, multiplication and division.
• Modulo arithmetic: addition and multiplication.
• Casting out nines.
• Primes: explore and test, prime factorization.
• The Sieve of Eratosthenes.

The built-in online help explains the various modes and what is expected of the user for each one.

Platform Requirements

The IntegerZone is an applet written using JDK 1.1. On Windows 95 it has been tested to run with Microsoft Internet Explorer 4.0 and Netscape Communicator 4.5. (It will not work with any earlier versions, it should work with later ones.) It can also be run as an application by invoking the Java class philipdorrell.izone.IntegerZone, for example using the JRE which can be downloaded from java.sun.com. Feedback from users on other platforms will be greatly appreciated.

(All platform names are trademarks of their respective owners.)

Installation

As it is a Java applet, you can run it just by going to the IntegerZone applet page (as long as you have Java switched on in your web browser).

Platform Differences

Window Resizing

One way in which IE 4.0 differs from JDK/JRE and Netscape is that it resizes window contents continuously as you resize the window border, as opposed to just once when you have finished resizing the window border. Furthermore IntegerZone resets cell sizes when the number of digits required changes. All of which makes it difficult for me to program perfect resizing behaviour (suggestions welcome). To avoid problems, a minimum size of 3 digits is set for cell size. You may notice problems in IE 4.0 if you resize the window showing numbers just below 1000, 10000, 100000 etc. (or -100, -1000 ...).

Don't let this discourage you from resizing the window, since changing the row width is an important part of the IntegerZone experience.