Logic gates

The three main gates are AND, OR and NOT.

Another way of visualizing the gates is in this site.

Some excellent visualisations of numbers This one is for prime number visualisation.

The Ulam spiral

The seive of Eratosthanes

Some numbers make a pattern

Some numbers make a pattern.

• x  y
• 1  1
• 2  2
• 3  3 
• 4  4
• 5  5

Some numbers are random

The sieve of Eratosthanes

Some we have to check for patterns

There are all sorts of ways to generate (pseudo) random numbers.

Current systems

Some older systems

One to one correspondence came first.

Editors come in all shapes and sizes.

There are people who always use special HTML editors to write their HTML scripts. Others use only simple text editors.


We often write HTML scripts in a text editor. There are many available and most are free.

Others are Notepad++, EditPlus and Ultra Edit. There is not a "best one" , they all have their own set of features. A lot of people just stick with Notepad in Windows and TextEdit on Macs. One of your tasks is to explore different text editors.

...and the best browser is...

A rating of all the common browsers is given in this site.

Also, look at this site ( the best browser is ..) and do the associated task. This has made some people review their favorite browser.

w3schools is a good website to learn about HTML