I am trying to program the 'sieve of eratosthenes' in visual basic. For those that don't know, it is an algorithm for making tables of primes. Sequentially write down the integers from 2 to the highest number n you wish to include in the table. Cross out all numbers which are divisible by 2 (every second number). Find the smallest remaining number . It is 3. So cross out all numbers which are divisible by 3 (every third number). Find the smallest remaining number . It is 5. So cross out all numbers which are divisible by 5 (every fifth number). Continue until you have crossed out all numbers divisible by , where is the floor function. The numbers remaining are prime. This procedure is illustrated in the above diagram which sieves up to 50, and therefore crosses out primes up to . If the procedure is then continued up to n, then the number of cross-outs gives the number of distinct prime factors of each number. (http://mathworld.wolfram.com/EratosthenesSieve.html [Broken]) I have some code. But how would you go about programming this? I have psuedocode in front of me and forgot to e-mail my other files to myself, but I will try to post what I have so far in the near future. I was thinking about doing it with listboxes, arrays, and 'for loops'.