1-11 is a numeric symbol used by the Aryan Knights, an Idaho-based prison gang, to identify themselves. Substituting letters for numbers, 1 and 11 mean A and K, i.e., Aryan Knights.

The number 12 is a numeric symbol for Aryan Brotherhood groups (as are the numbers 1 and 2 separately), especially the Aryan Brotherhood of Texas. Substituting letters for numbers, 12 equals AB, i.e., Aryan Brotherhood.

The number 13 is a numeric symbol for the Aryan Circle, the large Texas-based racist prison gang. Substituting letters for numbers, 1 and 3 equals A and C, i.e., AC or Aryan Circle.

The Aryan Circle is one of the largest white supremacist prison gangs in the United States. Its primary hand sign consists of holding up the thumb and the middle, ring, and little fingers of one hand, signifying the numbers 1 and 3 (which stand for AC). One can also hold up the little finger and the middle and index fingers, plus the thumb.