A Dozen and Two Sixes
what?
I submit that the most gameable number is 12. I ask you:
Why are there 12 months of the year?
12 zodiac signs?
24 hours in a day?
12 inches to a foot?
12 Apostles, 12 tribes of israel, 12 gods of Olympus?
Why do people all over the world still count like this?1 
Why are there secret societies dedicated to the proliferation of a duodecimal numeral system?
from Wikipedia:
The number twelve, a superior highly composite number, is the smallest number with four non-trivial factors (2, 3, 4, 6), and the smallest to include as factors all four numbers (1 to 4) within the subitizing range, and the smallest abundant number. [...] There is also higher regularity observable in the duodecimal multiplication table. As a result, duodecimal has been described as the optimal number system.
Using twelves in dice rolling games
12 is easily divisible into whole numbers in various ways, giving it an edge in intuitive, quick, dirty, personal-scale calculations. Everyone knows their way around a twelve.
Daniel Sell, author of the famously dozenmaxxing and 12pilled RPG Troika! was recently posting on Bluesky about overland travelling rules. I noticed immediately that his suggestion of being able to travel 12 leagues in a day was precisely similar to my own concept of 12 legs in a day.
I think the similarity, rather than being coincidence, is directly due to the number 12's many virtues.
Sell's system also neatly dovetails into each league costing a point of Stamina; most characters have a Stamina score between 12 and 24, so travelling for half the day to lose 1/4 or 1/2 of your Stamina feels reasonable.
This pleasing numeracy is actually a very common theme when hacking Troika!, and I reckon it all has to do with the number 12.
Six sided die can be used to generate all kinds of useful number ranges -- the famed 2d6 bell curve, the d36 or d66 table, even d6 dice pools.
(The d12 dodecahedron is also factually the prettiest die.)
Finally, basing your lore around multiples of 12 gives it an arcane, pre-Enlightenment twinge that echoes old religions and pre-Arabic numeracy. It's vibey man!
now what?
If i need a number, I'm reaching for 12.
Making a system and want it to 'click' at the table? Use 12.
Table? 2d6, 1d36, or 1d66.
Number of NPCs or factions? 6 or 12.
Lair populations? Multiples of 12.
Loot? Multiples of 12 also. (super useful for divvying up coin hoards).
use your thumb to track knuckle bones in your hand. By counting digits on 1 hand and sets of 12 on the other, you can count to 144 on your hands. pretty cool!↩