Definition:Octal Notation

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Octal is another word for base $8$.

That is, every number $x \in \R$ is expressed in the form:

$\ds x = \sum_{j \mathop \in \Z} r_j 8^j$


$\forall j \in \Z: r_j \in \set {0, 1, 2, 3, 4, 5, 6, 7}$

Also known as

Octal notation is also known as octonary or octenary.


Example: $371 \cdotp 24$

The integer expressed in octal as $371 \cdotp 24$ is expressed in decimal to $2$ decimal places as $249 \cdotp 31$.

Also see

  • Results about octal notation can be found here.

Historical Note

Octal notation was advocated by Emanuel Swedenborg.

Octal notation used to be important in the field of computer science, but is less so nowadays, as hexadecimal has proved itself more convenient in general.