Primes and Factors

Prime numbers- A prime number is a positive integer that has exactly two positive integer factors, 1 and itself. A couple of examples of prime numbers would be, 1,2,5,7,13 and so on and so forth. By using The Sieve of Eratosthenes we can eliminate all the numbers between 1-100 that are not primes. The first step is to eliminate all the numbers that end with an even number because we know that they are divisible by 2 but don't eliminate 2 so far because they are prime, then next we have to eliminate all multiples of a number (except itself). In the end we wind up with about 25 prime numbers between 1-100. You could all take the square root of the highest number that you have and the square root of that number check all the numbers below it and then the rest would be primes.


What I thought when going through my math book was the historical highlight about the Pythagorean, who were a brotherhood f mathematicians and philosophers who believed that numbers have special meanings that could account for all aspects of life. For more on the Pythagoras the founder click here. So the number theory is the study of nonzero whole numbers and their relationships. One important type of relationship in number theory is that between a factor and a multiple. If one number is a factor of a second number or divides the second then the second number is a multiple of the first.

For more examples of factoring and multiples click here. Here is a website that would be easy for children to understand factors and multiples better.