# Calculate Prime Numbers with Perl

There are several ways to calculate primes. Probably, the most efficient one is recursively dividing a number with all primes lower than the number itself. Since no primes are divisible by numbers other than themselves and 1, it would be possible to divide a number with all numbers below it. All numbers are essentially built up of primes, and therefore we can safely skip dividing by numbers which are not primes themselves, speeding up the process significantly.

``` 1 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 31 # The array where the primes will be stored my @primes = 2; # The maximum number of iterations my \$max = 100; # The starting iteration my \$i = 2; # Whether the current loop is to be broken my \$b = 1; # Start the loop while \$i < \$max # Check for each prime which has already been calculated foreach \$n @primes # If that prime is not divisible by the the current number.. if !\$i % \$n # ..break the loop \$b = 1; next; # If the loop was supposed to be broken, if \$b # reset \$b \$b = 0; # If not, else # add the number to the prime array push @primes, \$i; # Increment \$i \$i++; ```

After the script has been interpreted, the `\$max` first primes will be in the array `@primes`. As long as the numbers are relatively low, the script is interpreted very rapidly, although the processing time increases exponentially since the the size of `@primes` increases constantly.ringtones i dterm seriescell dying ringtoneringtones edit and makeelk buggle ringtonelll episode ringtonesfree ringtone polyphonic sony ericssonringtones ericsson w810iezdvd ringtone registryfix Map