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Welcome to my math blog! The purpose of this blog is to help you stay informed about our learning and experiences that have taken place during our math class. I have also included links your child (and you) may want to use in order to supplement math learning in 5th grade.

Wednesday, January 7, 2015

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

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