Here's a special one for you!
I am prime, I am composite
Sum my digits and half; I'll be perfect!
Don't multiply them, I won't yield a thing
But don't worry, it's only the beginning!
What am I?
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3 Answers
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Hoping this is good
$2019$
I am prime, I am composite
Prime as in beginning and composite as $2019 = 3\cdot673$
Sum my digits and half; I'll be perfect!
$2 + 0 + 1 + 9 = 12$, then $12/2 = 6$
Don't multiply them, I won't yield a thing
$2 \cdot 0 \cdot 1 \cdot 9 = 0$
But don't worry, it's only the beginning!
Happening around the world today!
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$\begingroup$ Yes, you got it! Prime can also mean importance, and it is so for a new year :) $\endgroup$ Dec 31, 2018 at 15:00
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2$\begingroup$ Would the wording "Sum my digits and halve" be better? $\endgroup$ Jan 1, 2019 at 22:23
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I'm thinking it might be
$39$
$(3+9)/2=6$, a perfect number as its factors sum to the number itself: $1+2+3=6$
$3$ is prime and $9$ is composite
Multiplying them won't yield just a thing, it yields $3\times 9=27$ things
I am a bit hung up on this but perhaps $39$ is the beginning of a sequence where these rules hold true (i.e., it's the smallest number produced by these rules). Or perhaps it's the first two of this series: $3^1, 3^2, 3^3, \cdots$
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1$\begingroup$ @SPK.z I can't believe I made that mistake. I'll edit. $\endgroup$ Dec 31, 2018 at 14:48
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Partial:
Are you
1?
I am prime, I am composite
Some say 1 is prime, some say it is composite
Sum my digits and half; I'll be perfect!
? Perfect number? Perhaps not
Don't multiply them, I won't yield a thing
any n*1 yield n
But don't worry, it's only the beginning!
beginning of natural numbers
answered Dec 31, 2018 at 14:35
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$\begingroup$ Nope (1 isn't conventionally a perfect number) ;P $\endgroup$ Dec 31, 2018 at 14:48
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2$\begingroup$ Technically 1 is neither prime nor composite. $\endgroup$– user33097Dec 31, 2018 at 15:44
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1$\begingroup$ To note, a "perfect number" is a number whose factors sum to twice that number, or one whose factors (excluding itself) sum to the number itself. $\endgroup$ Jan 1, 2019 at 10:56