


What is a Prime Number? Prime number has been fascinating for many great scientists and mathematicians for many centuries. Some people think that prime number contains some magic or mystics because of its irregularities and uniqueness. Prime number is a positive integer number greater than 1 that divisible only by that number itself and one. For example 2, 3, 5, 7, 11, 13, 17, 19 are the first eight prime numbers. For technical reason, one is not called a prime number. Example:
There are infinitely many prime numbers. Knowing about prime number, we can now divide any positive integer greater than 1 as either prime or not prime (also called composite number). A composite number has many divisors between 1 and that number, while prime number has no other divisor except 1 and that number. Example:
Now I would like to ask:
Below is an online interactive program that can help you to determine whether a positive integer is a prime or not. (Note: when your number is larger than 12 digits, you may have to wait to get the answer). Try to answer the following questions using this tool:
In the next section, you will learn and have more fun on how to test whether a number is a prime number or a composite number using an algorithm called Sieve of Erastosthenes. Preferable reference for this tutorial is Teknomo, Kardi (2010) Prime factor tutorial. http:\\people.revoledu.com\kardi\ tutorial\BasicMath\Prime\ 



