We all studied in high school mathematics that a prime number is a natural number that is not a product of two smaller natural numbers. There are many such numbers and mathematicians have developed various algorithms to find the prime numbers.

One of the most ancient algorithms to calculate all the prime numbers was developed by the Ancient Greeks and is called the Sieve of Eratosthenes. This is basically a repeated elimination algorithm where you have to remove all the natural numbers that are multiples of smaller numbers.

Now on your Windows PC, you can calculate prime numbers using a freeware called Prime Number Counter. As the title of the software suggests, it can count the number of prime numbers up to a limit or until stopped. In the Prime Number Counter, we have to pick one of the three methods – slow, fast or fastest. However, the program does not explain what is the difference between these methods and what makes them slow or fast. We can also choose whether it should calculate the prime number up to a certain limit or whether it should keep calculating until stopped by the user.

Clicking on the “Count Prime Numbers” button will initiate the calculation process and clicking on the same button will stop it. The calculated numbers list can be saved to a text file which can be printed or you can read it on your favorite text editor such as Notepad++.

The program displays the total number of prime numbers that it has found as well as the last prime number calculated. It also shows the total time taken to do the calculation. For the fastest method, it took 0.25 seconds and calculated 9592 prime numbers. The time taken is also an indicator of how good your computer hardware is.