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Digital Roots

  1. Nov 28, 2014 #1
    Digital root (adding a number's digits together repeatedly until a single digit answer is obtained) doesn't seem like a very interesting operation, but it has some weird properties. One of the first someone might notice is that
    dr(n) = dr(n+9)
    This is fairly easy to demonstrate. But after graphing the digital roots of the first 9 multiples of n with values of 9 from 1-9, a seemingly uninteresting operation looks pretty cool. Notice how dr(n) always goes through (9/2, 9/2)
    Doesn't really have any implications towards anything but looks pretty cool.

    Attached Files:

  2. jcsd
  3. Nov 28, 2014 #2


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    This technique can be used to determine if a large number is a multiple of 9 - with single digit of 9, or a multiple of 3 - single digit 3, 6, or 9.
  4. Nov 28, 2014 #3
    Each number has a digital root pattern, that's for 3. For example, 4 is 4,8,3,7,2,6,1,5,9
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