Re: Why not 13 months? (Was La Systeme Metrique)

Stephen Souter (
7 Aug 1995 08:22:58 GMT

In article <3v34ub$>, (Whittet) wrote:

> In article <>,
> says...
> >
> >The chief problem is that 13 happens to be a prime number. This makes it
> >mathematically impossible to subdivide a year in any satisfactory fashion.
> >You cannot even divide such a year into the customary four seasons and
> >hope to come out with the same number of whole months in each season.
> >
> >By contrast, a 12-month year can be easily divided into halves
> >(six-monthly periods), quarters (3-monthly), thirds (4-monthly), and
> >sixths (bimonthly) of more or less equal size.
> try four seasons of 91 days = 364 days
> 13 x 7 = 91
> thus the year of 13 months can be divided into 4 seasons of 13 weeks !

Of course you can divide it in this fashion. After all, 52 weeks is evenly
divisible by 4, just as 364 days (but not 365 or 366!) is evenly divisible
by 4.

Personally, I would find it easier remember that there are 3 months per
season than to have to recall that seasons are made up of 91 days or 7
weeks (except for one which would have to have 92 days, or 7 weeks plus
one day...not counting leap years, when *two* quarters would have 92 days
or 7 weeks plus 1 day). Months allows us to leave all the fiddly
calculations about the exact number of days per quarter to the computers!

But that aside, I fear you are missing the point.

How many *whole* months are there in 13 weeks?

More to the point, you can subdivide 12 months in no less than 5 different
ways. How many ways can you subdivide 13 months--or for that matter 52
weeks or 364/365/366 days--and have them come out in nice round numbers?

Stephen Souter