Prime Numbers
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The following numbers are prime: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29,
31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109,
113, 127, 131, 137, 139, 149, 151, 157, 163 ,167, 173, 179, 181, 191, 193, 197,
199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281,
283 and 293.
This means that all other numbers between 2 and 300 are composite. (i.e.
4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20, etc.)
How to find prime and composite numbers
To find prime and composite numbers, you can make a table as in the
example that follows.
(Prime numbers are in bold and composite numbers
have been striken through.)
| | 2 | 3 | 4 | 5
| 6 | 7 | 8
| 9 | 10
|
| 11 | 12 | 13
| 14 | 15 | 16
| 17 | 18 | 19 | 20
|
21 | 22 | 23
| 24 | 25 | 26
| 27 | 28 | 29
| 30
|
What to do:
- Create a table, like the above, with all the numbers you would like.
Be sure to line them up in some nice fashion, it will come in helpful later.
- Once you have all of the numbers in nice rows, circle the first prime
number you come across. (If you are doing this right, it would be: 2.)
(We could not circle the above, so instead we used the bold formatting.)
- Now, since the definition of a prime number is: a number that is
divisible only by itself and one. You can cross out all multiples of
2. (i.e. 4, 6, 8, 10, 12, 14, 16, 18, 20 ...) (Tip: To make this somewhat
easier on you, just take the column that starts with 4 and cross the entire
column out. Do the same for 6, 8 and 10. Do the same thing with the 2 column,
but do not cross out the 2.)
- Now repeat steps 2 & 3 until you have reached the end of the table.
The first prime number in this second case would be #3. If you notice,
it has not yet been crossed out. Then do the same with 5, but just circle
five and cross out everything else in the column.
Links
The Prime Page (the prime source for information about prime numbers)
Home: Math: Prime Numbers
schester@la.znet.com
Last Update: 12 August 1997
Copyright © 1996-1997 Scott Chester
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