Prisoner markings and IDs

Hey there.
I was at a motorcycle rally the other day—just soaking up the atmosphere—and I couldn't help but notice a handful of tattoos that seemed to carry some sort of hidden "meaning."😕
After a rather half-hearted attempt at Googling, I came up with absolutely nothing of substance. Typical.
Does anyone here actually know what all these body markings signify? For instance, things like a number 8 ball, or the number 13... I think I know the deal with 81, but my knowledge hits a brick wall after that.

88-
The eighth letter of the alphabet is H
which means HH stands for Adolf Hitler 🤮
I’ve noticed a few people using that

Look, I get the whole thing about letters—it’s all just semantics, really. It's the exact same logic behind why the Hells Angels switched to using "81" instead of their actual patch; they got hit with those legal injunctions here in the States over their symbols, so they just pivoted to numbers to stay under the radar.
So, what else have you got?