Math Is Fun Forum

Stanley_Marsh

Member

Registered: 2006-12-13

Posts: 345

About the prime factoring

I 've though of sth , but don't know whether it's useful or not , but can speed up a little

For example ,  the number 679543

if

we just need to find p.

But the range is still to large , then assume 679543=qpm , then 

Assume that  679543=abcd , then

Try , 23,19,17,13,11, 7 5, 3, 2, ,find out that none of them can divide the number , then the number may be the product 3 primes or 2 primes .
   I don't know if this can help.

Last edited by Stanley_Marsh (2007-03-17 16:38:33)

---

Numbers are the essence of the Universe

Stanley_Marsh

Member

Registered: 2006-12-13

Posts: 345

Re: About the prime factoring

I think as the number increases , prime become more rare , it'll be easier to do it.

---

Numbers are the essence of the Universe

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: About the prime factoring

I think that would have limited use. You're right that it would help to deduce how many prime factors a number had, but knowing that doesn't help you to find what they are.

Primes do become a bit rarer as you get to higher numbers, but not so much that it becomes easy to try them all out.

---

Why did the vector cross the road?
It wanted to be normal.

Stanley_Marsh

Member

Registered: 2006-12-13

Posts: 345

Re: About the prime factoring

it can narrow the range and eliminate the number of primes whose product is the number.

I have to work on this some more .

Last edited by Stanley_Marsh (2007-03-18 07:54:36)

---

Numbers are the essence of the Universe