Math Is Fun Forum

I got this from Wikipedia:

"Until the 19th century, most mathematicians considered the number 1 a prime, with the definition being just that a prime is divisible only by 1 and itself but not requiring a specific number of distinct divisors. There is still a large body of mathematical work that is valid despite labelling 1 a prime..." 

So, to my mind, it's debatable.  I personally consider 1 to be prime, for the simple fact that it's not "compound." For me, all natural numbers (the "counting numbers": 1,2,3,4,5,6...infinity) can be put into 2 groups: either prime or compound (reducible to factors that are primes).  And there's no way 1 should be considered compound.  And having 3 groupings of natural numbers, {primes}, {compounds}, and {1}, seems silly and inelegant.

And I hardly think saying 1 is prime is in any way like saying 2+2=5, or pi=3.0, or 1/0=0, all of which are clearly false.

To be, or not to be (prime). That is the question (for One).  I'm sure the validity of Mathematics will not collapse in either case.