This part of the program calculates all prime numbers and all twin primes between two given numbers. The result may be directed to the screen, to the printer or to the file PRIM.TXT .
Prime numbers are all the natural numbers with exactly two divisors.
Hence number 1 is not a prime number and number 2 is the only even prime number. Euklid already proved that there exists an infinite number of prime numbers. And it is proven too that the intervals in the sequence of primes are not limited whatsoever. Twin primes are two primes with a difference of two e.g. 10007 and 10009 or 1000018709 and 1000018711. If the difference between the upper and the lower limit exceeds 50000 the range is automatically limited to 50000.