The Excel Bin2Oct function converts a Binary (Base 2) number into an Octal (Base 8) number.
The syntax of the function is:
Where the function arguments are as follows:
number    The binary number that is to be converted to octal. 
[places]   
An optional argument, which specifies the number of characters that you want the returned octal number to have. If this is greater than the minimum, the octal number will be padded out using leading zeros. If omitted, the returned octal uses the minimum number of places. 
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.
+ Display Binary and Octal Summary:
The Binary (Base 2) Numeral System uses the digits 0 & 1.
The following table shows the first 8 binary values, along with the equivalent decimal values:
Binary  1  10  11  100  101  110  111  1000 
Decimal  1  2  3  4  5  6  7  8 
For further information on the binary numeral system, see the Wikipedia Binary Page
The Octal (Base 8) Numeral System uses the digits 07.
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 
The following spreadsheets show five examples of the Excel Bin2Oct function.
Formulas:

Results:

Note that, in the above example spreadsheet, the negative binary and octal numbers in cell A4 are represented by two's complement notation.
Further details and examples of the Excel Bin2Oct function are provided on the Microsoft Office website.
If you get an error from the Excel Bin2Oct function this is likely to be one of the following:
#NUM!   
Occurs if either:

#VALUE!    Occurs if the supplied [places] argument is nonnumeric. 