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.