Duodecimal numbers are built out of the $12$ digits, $0,1,2,3,4,5,6,7,8,9,A$ and $B$, although some people use other symbols such as an upside down $1$ for $A$ and an upside down $2$ for $B$.

The duodecimal system is a Base-12 number system.

Another name for the duodecimal number system is the dozenal number system.

The following are some examples of duodecimal numbers:

• The duodecimal number $A$ is equal to the decimal number $10$
• The duodecimal number $B$ is equal to the decimal number $11$
• The duodecimal number $10$ is equal to the decimal number $12$
• The duodecimal number $100$ is equal to the decimal number $144$
• The duodecimal number $110$ is equal to the decimal number $156$
• The duodecimal number $111$ is equal to the decimal number $157$
• The duodecimal number $129AB$ is equal to the decimal number $1 \times 12^4 + 2 \times 12^3 + 9 \times 12^2 + 10 \times 12 + 11 = 25,619$.