If you have very accurate time of birth, observe where the twelfth-part of the Ascendant falls, some very valuable information about your personality can be revealed by the sign where this twelfth part falls.
Each sign is divided into twelve parts where every part gets 2.5 degrees. First part is always dedicated to the actual sign and the next to the next sign in order, etc. So the twelfth parts of Aries start with Aries, Taurus, Gemini, Cancer, and so on. The sequence of twelfth-parts of Taurus starts with Taurus, Gemini, Cancer, Leo, and so on. To find where the twelfth-part of particular planet lies you may use little bit of mathematics with your calculator. Let’s say my Moon lies in 06°15′ Scorpio.
I multiply 6 with 12 and get 72. Now I multiply the minutes with 12 too and get 15 x 12 = 180. Now to convert the minutes into degrees I divide 180 with 60 (number of minutes in one degree) and get 3. 72 + 3 = 75. The twelfth part of my Moon will be 75 degrees away from the beginning of Scorpio. Important thing, you start counting not from 6°15′ Scorpio where Moon is placed, BUT from the beginning of the sign of Scorpio. So the twelfth-part of Moon will fall in 15° Capricorn.
Morinus freeware software gives these twelfth-parts visually in the chart so you don’t need to calculate anything.
Some other names for the twelfth-parts: dodekatemoria, duodecima or plural duodecimae, duads, dwads, etc.
To find them approximately without calculator you may use this simple trick.
If a planet is in the beginning of a sign (from 0° to 2°30′) then the twelfth part of that planet will be in the same sign.
If from 2°30′ to 5° – in the sign next to it.
If a planet is from 5° to 7°30′ (as in our example with Moon above) then the twelfth-part of that planet will be in the sextile sign following the sign where the planet is found.
If a planet falls from 7°30′ to 10° the twelfth-part will fall in the square following.
If a planet falls from 10° to 12°30′, the twelfth-part will fall in the trine following.
If a planet falls from 12°30′ to 15° it will be the quincunx sign from the planet.
15° to 17°30′ is easy to remember, the twelfth-part falls in the sign opposite.
From 17°30′ to 20° it is in the second quincunx, the one behind the sign in question.
From 20° to 22°30′ the trine behind.
From 22°30′ to 25° the square behind.
From 25° to 27°30′ the sextile behind.
From 27°30′ till the end of sign, in the sign behind it.
Commit this to memory and you will not have a problem finding the twelfth-part of any planet, at least by sign if not by degree.
Remember the 0 – 2.30 segment, the 5 – 7.30 segment that leads to sextile in front and the 25 – 27.30 that leads to sextile behind. The 15° segment leads to opposite sign and the 10-20 segments leads to trine in front and trine behind respectively. Once you know these, the intermediate you would easily reckon.