Is Eleven and Twelve decimal?

was asked by a classmate that the decimal system is not full decimal. Are 11 and 12 decimal?

Jan.18,2022

usually learn the decimal system, 11, 12 have two digits, out of the environment who knows how many digits.

Common:
Octal 11 equals 10
Octal 12 equals 10
hexadecimal 11 equals 10
hexadecimal 12 equals 10
10 binary 11, 12 is our usual 11, 12

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