WHAT
SO SPECIAL ABOUT NUMBER 9?
Number 9 is
the natural number following 8 and preceding 10.
In the NATO
Phonetic alphabet, the digit 9 is called "Niner".
Five-digit produce
PLU codes that begin with 9 are organic.
Common terminal digit
in psychological pricing.
Consider to Chinese
culture is Nine is a good number in Chinese culture because it sounds
the same as the word "long lasting".
In the case of the
number 9, however, the math highlights a philosophical observation that is
unique, interesting and very revealing.
Nine is
a composite number, its
proper divisors being 1 and 3. It is 3 times 3 and
hence the third square number. Nine is a Motzkin number. It is the first
composite lucky number, along with the first composite odd number.
Nine is the highest
single-digit number in the decimal system. It is the second non-unitary square prime of
the form (p2) and the first that is odd. All subsequent squares of
this form are odd. It has a unique aliquot sum 4 which is itself a
square prime. Nine is; and can be, the only square prime with an aliquot sum of
the same form. The aliquot sequence of nine has 5 members (9, 4, 3, 1,
and 0) this number being the second composite member of the 3-aliquot tree. It
is the aliquot sum of only one number the discrete semi prime 15.
There are nine Hedger
numbers.
Since 9 = 321,
9 is an exponential factorial.
8 and 9 form
a Ruth-Aaron pair under the second definition that counts repeated
prime factors as often as they occur.
In bases 12, 18 and 24,
nine is a 1-automorhic number and in base 6 a 2-automorphic number (displayed
as '13').
Source by Wikipedia.com
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