Taylor - Theoretic Arithmetic.pdf - Platonic Philosophy

Egyptians that the death of Osiris happened on the 17th day of
the month, at which time it is especially evident that the moon
is at the full. Hence the Pythagoreans call this day antiphraxis,
obstrzlction, or opposition, and utterly abominate this number.
For 17 falling as a middle number, between the square 16, and
18 an oblong number, (which are the only plain numbers that
have their ambits equal to the spaces contained by the ambitsj
it opposes and disjoins them from each other, and being divided
into unequal portions forms the sesquioctave ratio;" (viz.
by a division into 9 and 8.)
But that the ambits of these two numbers 16 and 18 are
equal to their areas is evident. For 16 is a square each side of
which is 4, and the number of the sides is 4. And 18 may be
conceived to be a parallelogram the four sides of which are 6,
6, 3, 3, the sum of which is 18.
It is observed by Martianus Capella, that if the number 5
either multiplies itself, or any odd number, the product always
ends in 5. And I have observed of 6, which when multiplied
by itself always ends in 6, that if it multiplies an even number,
the product will always end in that even number itself, which
it multiplies, or the final number of it. Thus 2>(6=12; 4x6
=24; 6)(6=36; 8)