# A to Z of Excel Functions: the OCT2DEC Function

10 April 2023

*Welcome
back to our regular A to Z of Excel Functions blog. Today we look at the OCT2DEC function. *

** **

**The
OCT2DEC function**

This function converts an octal number (base eight) to a binary number (base two).

The **OCT2DEC **function
employs the following syntax to operate:

**OCT2DEC(number)**

The **OCT2DEC**function has the following arguments:

**number**:**number**cannot contain more than 10 octal characters (30 bits) and that the most significant bit of**number**is the sign bit. The remaining 29 bits are magnitude bits. Negative numbers are represented using**two's complement**notation.

**Two's
complement** is a mathematical operation on binary numbers, as well as a binary
signed number representation based on this operation. The two's complement of an **N**-bit number is defined as the
complement with respect to 2** ^{N}**;
in other words, it is the result of subtracting the number from 2

**. This is also equivalent to taking the ones' complement and then adding one, since the sum of a number and its ones' complement is all 1 bits. The two's complement of a number behaves like the negative of the original number in most arithmetic, and positive and negative numbers can coexist in a natural way.**

^{N}It should be further noted that:

- if
**number**is not a valid octal number,**OCT2DEC**returns the*#NUM!*error.

Please see my example below:

*We’ll continue our A
to Z of Excel Functions soon. Keep
checking back – there’s a new blog post every other business day.*