Sieve of Eratosthenes (Prime or Composite)

Today we worked with the Sieve of Eratosthenes.  This procedure was a way to separate prime and composite numbers using their factors.

A prime number has only two factors:  1 and itself.

A composite number has more than two factors.

Using this information and a hundreds chart, we found the prime numbers between 2 and 100.  In the process we found out some interesting facts:

• 1 is NEITHER prime nor composite as it only has 1 factor.
• 2 is the ONLY EVEN PRIME number.

To see our lesson and to see how the "sieve" works, please watch the video:  Prime or Composite?

HOMEWORK:  Countdown 1.3