The duodecimal (also known as base-12 or dozenal) system is a numeral system using twelve as its base.
The number ten may be written as A, the number eleven as B, and the number twelve as 10. The number 12 has six factors, which are 1, 2, 3, 4, 6, and 12. It is a more convenient number system for computing fractions compared with the decimal or vigesimal systems. The decimal system has only four factors, which are 1, 2, 5, and 10.