Seeker of Carcosa

I have no eye for this, but around 110% looks like a normal person’s face to me.

For me it’s Grothendieck’s prime.

Divisibility by 3 rule is real. If the sum of the digits of a number is divisible by 3, then the number itself is also divisible by 3. Same goes with 9. There’s an 11 rule, but it’s a bit convoluted.