Loading ...
Sorry, an error occurred while loading the content.

25169Re: Multiplying Primes and Numbers in General

Expand Messages
  • mikeoakes2
    Jun 4, 2013
    • 0 Attachment
      --- In primenumbers@yahoogroups.com, "G Fischer" <golfbum71@...> wrote:
      >
      > Hit send again and realized I misspoke below for the 6N+1 multiplied by 6N-1
      > numbers...
      > c = 6ab + a - b
      > This formula will show differently since a and b can be different... when
      > the numbers are interchanged.
      >
      > As an example: 59*67 = 3953
      > The formula for c in this case is: c = 6ab + a - b
      > a = 10
      > b = 11
      > c = 659
      > c = 6*10*11 - 10 + 11
      > c = 660 + 1
      > c = 661
      >
      > and flopped:
      > a = 11, b = 10, c = 659
      > c = 6*10*11 - 11 + 10
      > c = 660 - 1
      > c = 659
      >
      > Perhaps a rule for whichever number is 6N-1 is added and 6N+1 is subtracted?

      It's not complicated at all, Geoff, it's just high-school algebra.

      Let the 2 numbers be x=6*a+a1 and y=6*b+b1, where a1 and b1 are each either +1 or -1.
      Then x*y = (6*a+a1)*(6*b+b1) = 6*c+c1,
      where c = 6*a*b+a1+b1,
      and c1 = a1*b1 (= +1 or -1).

      Mike
    • Show all 7 messages in this topic