jump to navigation

ល្បងខួរក្បាល ខែ​មេសា 8, 2009

Posted by psvjupiter in Uncategorized.
trackback

ចូររកវិធីមួយដើម្បីអោយអ្នកអាចបង្កើត ២០០៩ ចំនួនគត់តគ្នា ហើយចំនួននីមួយៗសុទ្ឋតែមិនមែនចំនួនបឋម។
Find a way to produce a sequence of 2009 consecutive numbers of which non is prime.
Example of 5 consecutive number : 48 49 50 51 52 (All 5 are not prime number) how abt 2009?

មតិ»

1. kienforcefidele - ខែ​មេសា 9, 2009

That seems a lot. 2009 numbers?😕

2. psvjupiter - ខែ​មេសា 9, 2009

It is not that difficult once you know that it is possible even 10000000 consecutive numbers non is prime😀. Use yr brain

3. psvjupiter - ខែ​មេសា 10, 2009

Hint : Think of 2010 factorial!
2010!

4. psvjupiter - ខែ​មេសា 11, 2009

ចំលើយ
ស្វីតនោះអាចជា​
2010!+2
2010!+3
2010!+4
………….
………….
………….
2010!+2010

5. kienforcefidele - ខែ​មេសា 12, 2009

how do you know that?😕

6. psvjupiter - ខែ​មេសា 12, 2009

SORRY don’t get you mean ? You ask me how i know the solution or how do these sequence satisfied condition?

7. ពិសិដ្ឋ - ខែ​មេសា 12, 2009

ជួយ​សរសេរ​ដំណោះ​ស្រាយ​មួយ​មក !!!

8. psvjupiter - ខែ​មេសា 12, 2009

Oh, there is no solution. We can see easily that
2010!+2 divide 2 hence not prime
2010!+3 divide 3 hence not prime
……………..
2010+2010! divide 2010 hence not prime
(because 2010=1x2x3x4x….x2010)
So none of them is prime. Indeed there are 2009 number here (from 2 to 2010) so we complete problem objective

in general to generate a n consecutive non prime number we use the sequence (n+1)!+k where k is from 2 to k+1……
Get what i mean?

9. ពិសិដ្ឋ - ខែ​មេសា 12, 2009

អរគុណ​ចំពោះ​ដំណោះ​ស្រាយ​! ខ្ញុំ​យល់​ខ្លះ មិន​យល់​ខ្លះ តែ​នឹង​ព្យា​យាម​យល់​ឲ្យ​បាន​ច្រើន​។

10. psvjupiter - ខែ​មេសា 12, 2009

Oh i will try to explain again.😀 it is ok.
First you need to know factorial definiton
Definition n! pronounce as n factorial is equal to 1X2X3X4X……..X n
so 3!=1X2X3=6
6!=1X2X3X4X5X6=720
and the same 2010!=1x2x3x4x5x…..x2008x2009x2010
hence number [2010!+k] such that k<=2010 will never be prime why
because 2010!=1x2x3x…x k x(k+1) x(k+2)x….x2010
so 2010!+k is divided by k
value k from 2 to 2010 then we will get 2009 consecutive number…..
2010!+2, 2010!+3,……2010+2010.
non of which is prime. 😀 hope it help this time.

11. kienforcefidele - ខែ​មេសា 14, 2009

so, for the 10000000 consecutive numbers which none is prime:
10000001!+2
10000001!+3
10000001!+4
…………………
…………………
10000001!+10000001
Is that right?🙂

12. jupiter - ខែ​មេសា 14, 2009

yes it is. I think it is not difficult to understand isn’t it? Every term of U(n) if divide by n. say U(500)=10000001!+500 is divide by 500
because 500 include in 1000001!

13. kienforcefidele - ខែ​មេសា 14, 2009

yeah, I understood! Thanks😀 I was so dumb anyway, the answer was right in front of me when you gave the hint, but I just couldn’t see it.


ឆ្លើយ​តប

Fill in your details below or click an icon to log in:

ឡូហ្កូ WordPress.com

អ្នក​កំពុង​បញ្ចេញ​មតិ​ដោយ​ប្រើ​គណនី WordPress.com របស់​អ្នក​។ Log Out / ផ្លាស់ប្តូរ )

រូប Twitter

អ្នក​កំពុង​បញ្ចេញ​មតិ​ដោយ​ប្រើ​គណនី Twitter របស់​អ្នក​។ Log Out / ផ្លាស់ប្តូរ )

រូបថត Facebook

អ្នក​កំពុង​បញ្ចេញ​មតិ​ដោយ​ប្រើ​គណនី Facebook របស់​អ្នក​។ Log Out / ផ្លាស់ប្តូរ )

Google+ photo

អ្នក​កំពុង​បញ្ចេញ​មតិ​ដោយ​ប្រើ​គណនី Google+ របស់​អ្នក​។ Log Out / ផ្លាស់ប្តូរ )

កំពុង​ភ្ជាប់​ទៅ​កាន់ %s

%d bloggers like this: