# The Excel OCT2DEC Function

Related Function:
Dec2Oct Function

## Function Description

The Excel Oct2Dec function converts an Octal (a base-8 number) into a decimal number.

The syntax of the function is:

OCT2DEC( number )

Where the number argument is the octal number that is to be converted to a decimal.

Note that the supplied number argument must not be more than 10 characters (40 bits) long. The most significant bit of this value denotes the sign of the number and the remaining 39 bits denote the magnitude. Negative numbers are represented using two's complement notation.

Octal

The Octal (Base 8) Numeral System uses the digits 0-7.

The following table shows the first 16 octal values, along with the equivalent decimal values:

 Octal 1 2 3 4 5 6 7 10 11 12 13 14 15 16 17 20 Decimal 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

For further information on the octal numeral system, see the Wikipedia Octal Page

## Oct2Dec Function Examples

The following spreadsheets show five examples of the Excel Oct2Dec function.

Formulas:
A
1 =OCT2DEC( "10" )
2 =OCT2DEC( "22" )
3 =OCT2DEC( "0000000010" )
4 =OCT2DEC( "7777777770" )
5 =OCT2DEC( "355" )
Results:
A B
1 8   Result is   1*8 + 0
2 18   Result is   2*8 + 2
3 8   Result is   1*8 + 0
4 -8   Result is   -8^9 + 7*8^8 + 7*8^7 + ... + 7*8 + 0
5 237   Result is   3*8^2 + 5*8 + 5

Note that, in the above example spreadsheet, the negative octal in cell A4 is represented by two's complement notation.

Further details and examples of the Excel Oct2Dec function are provided on the Microsoft Office website.

## Oct2Dec Function Error

If you get an error from the Excel Oct2Dec function this is likely to be the #NUM! error:

Common Error
 #NUM! - Occurs if the supplied number argument is not recognised as a octal number, or contains more than 10 characters.