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 perfect numbers...
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Prince




PostPosted: Thu Feb 12, 2004 10:33 am   Post subject: perfect numbers...

i kno this is easy (mayb its jus my laziness) does sumone kno of a simple way to find perfect numbers?
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Tony




PostPosted: Thu Feb 12, 2004 10:36 am   Post subject: (No subject)

what's the definition of a perfect number?
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Prince




PostPosted: Thu Feb 12, 2004 10:40 am   Post subject: (No subject)

a number thats equal to the sum of its proper factors is a perfect number
Tony




PostPosted: Thu Feb 12, 2004 10:42 am   Post subject: (No subject)

hmm... forloop factors and see if they make up a perfect number Laughing
Latest from compsci.ca/blog: Tony's programming blog. DWITE - a programming contest.
Prince




PostPosted: Thu Feb 12, 2004 10:59 am   Post subject: (No subject)

lol umm could u explain that a bit Confused
Tony




PostPosted: Thu Feb 12, 2004 2:25 pm   Post subject: (No subject)

well I'm not too sure on the "proper factors" part... but assuming that any number can be a proper factor and you'll looking at numbers up to 100 assuming each has 2 factors only.
code:

for(i = 1; i<11;i++)
{
     for(i2 = 1; i2<11;i2++)
     {
          if (i*i2) == (i+i2) then
          { System.out.println(i+i2 + " is a perfect number); }
     }
}


Thought I donno... Confused it seems that there got to be a better way out there...
Latest from compsci.ca/blog: Tony's programming blog. DWITE - a programming contest.
wtd




PostPosted: Thu Feb 12, 2004 3:17 pm   Post subject: (No subject)

http://mathforum.org/dr.math/faq/faq.perfect.html

And quickly, the Quick BASIC program in the above page for finding Mersenne primes and their associated perfect numbers:

code:
  DEFDBL A-Y: DEFSTR Z: CLS
  mer = 1: two# = 1: power = 1: xm = y: x2 = y
1 power = power + 1: mer = mer + mer + 1: two# = two# + two#
  LOCATE 25, 1: PRINT "Testing"; mer;
  FOR i = 3 TO INT(SQR(mer + 1)) STEP 2: IF (mer MOD i) = 0 THEN 1
  NEXT
  LOCATE 24, 1: PRINT USING "#,###########"; mer;
  PRINT " = 2^"; LTRIM$(STR$(power)); "-1";
  IF power < 31 THEN
      PRINT TAB(36); USING "###,###########"; two# * mer;
    ELSE PRINT TAB(26); "2,305,843,008,139,952,128";
  END IF
  PRINT " = (2^"; LTRIM$(STR$(power)); "-1) * 2^"; LTRIM$(STR$(power - 1))
  IF power < 31 THEN 1
Cervantes




PostPosted: Thu Feb 12, 2004 5:10 pm   Post subject: (No subject)

um, anyways... google prime numbers you'll find a bunch of stuff.
its something like 2(n^2) (2n^2) where (2n^2) is a prime... dunno, kinda confusing.. google it though, you'll find a much better explanation Wink
MysticVegeta




PostPosted: Fri May 06, 2005 5:56 pm   Post subject: (No subject)

Tony wrote:
well I'm not too sure on the "proper factors" part

Yes they are only proper factors.
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