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Prime Numbers in the Ancient World
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Jennifer Thieme

Jennifer Thieme is self-employed in the accounting field, having served small businesses for over nine years. She's certified in QuickBooks, and is a Registered Tax Preparer. Troubleshooting accounting sofware issues is her specialty.

On the personal side, she's interested in esoteric ideas and has studied them under the same teacher since 1985. Married since 1988, she home schooled her three beautiful children for ten years. Writing is one of her hobbies.

If you have questions about QuickBooks, drop Jennifer an email. Contact information is available at either link below.

 
By Jennifer Thieme
Published on 10/14/2006
 
Use these easy directions for finding prime numbers. Makes for a quick math lesson, plus a little history.

Prime Numbers in the Ancient World

Ok, I'll be the first to admit that I don't have a clue as to why prime numbers are important. My daughter asked, "Why do we need them?" After doing some research on the Internet to try to answer her question, the best I can come up with is that they have something to do with computer encryption technology. Why they were important prior to the advent of computers is beyond me. Nonetheless, I do find them interesting.

During my Internet research I came across easy directions to generate prime numbers. This set of instructions is ideal for any age student who needs to study this topic.

Eratosthenes, a genius who lived about 200 years before Christ, formulated this "sieve," which is extremely easy to use. Follow these directions to discover how easy it is to find prime numbers:

First, write down a list of integers. Start with the number two and go as high as you like. The example below goes up to twenty:

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Not including two, mark all multiples of two:

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Moving up to the next unmarked number, which in this case is three, do not mark it, but mark all its multiples:

2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Continue in this fashion, marking all multiples of the next unmarked number until there are no new unmarked numbers in your list. Draw a circle around all unmarked numbers that remain. If your list went up to 20, it should look like this:

2 3 5 7 11 13 17 19

For a more effective lesson, make the list longer. Up to 50 is a good choice for a younger student; up to 100 might be better for an older student.

To make this a "thematic" or "unit" study, do some research on Eratosthenes and incorporate what you find into the lesson. He's an interesting historical figure and is worth studying all on his own.

I still don't know why we need prime numbers, and I still don't know why I find them interesting. If I figure these things out, I'll let you know.

About the Author:

Jennifer Thieme began homeschooling her three children in 1996. She is the administrator of a small, private ISP she established for her own family and several of her friends. Her homeschooling articles have appeared in Practical Homeschooling, and her business articles have appeared in Intuit's Pro Connection Newsletter.

She operates a bookkeeping, tax, payroll, and QuickBooks support service. Visit her business website: Solid Rock Accounting Services.