Next, Jade!
Her birthday is December 1st. Which is 12-2. And together 121. 1+2+2= 4. Who’s the fourth sign in the Zodiac? Cancer!! Thus Jade’s patron troll is Karkat.
Rose:
December 3rd. 12-3. 123. 1+2+3= 6. Virgo is the sixth sign in the Zodiac. Thus, Kanaya is Rose’s patron troll.
Dave:
Dave:
December 4th. 12-4. 124. 1+2+4= 7. Libra is the seventh sign in the Zodiac. Thus, Terezi is Dave’s patron troll.
Woah man, did I just blow your mind? I hope so.
This also helps me remember all the kid’s birthdays.
Anyway, another example. My birthday is September 21, so 9-21, 921, 9+2+1=12. Thus my patron is Feferi. 
Another note, you may get an answer OVER 12! Do not fret, the next step is pulling up your calculator and dividing the sum by 12. If the product is 1.5 or less, your patron is Aradia. If it’s 1.6 or higher, it’s Tavros. (At least, these are guidelines I go by.)
Anywayyy, thanks for reading. Just, the whole “I’m a Virgo thus my patron is Kanaya” thing is one of my pet peeves!
And for your reference:
1 - Aradia
2 - Tavros
3 - Sollux 
4 - Karkat
5 - Nepeta
6 - Kanaya
7 - Terezi
8 - Vriska
9 - Equius
10 - Gamzee
11 - Eridan
12 - Feferi