Here's the Sieve of Eratosthenes, the strategy of an ancient Greek mathematician to find prime numbers.
So, x=2, the first prime number. Write a list of numbers from x to y.
Cross out x's multiples, then do the same for the next uncrossed number. The ones crossed out are the composites, and the ones left are the primes, because primes have no factors other than 1 and itself, and composites have at least one more. so if y = 10, then the primes are:
2, 3, 5 and 7,
and the composites are:
4, 6, 8, 9, and 10.
Last edited by n872yt3r (2013-01-25 23:27:30)
Math Is Fun Rocks!
By the power of the exponent, I square and cube you!
I do not agree with the last sentence...
Here lies the reader who will never open this book. He is forever dead.
Taking a new step, uttering a new word, is what people fear most. ― Fyodor Dostoyevsky, Crime and Punishment