Dammit! Someone wrote up the nodeshell before me. Ah well, I'll write my version, and they can fight it out.
Write your binary number down. Here's mine:
11010111
Now, divide it up into groups of
three, starting at the
right. If the
leftmost group has less than three letters in it, put
zeroes at the start to
make it up to three.
011 010 111
Now, this is similar to
Binary to Hexadecimal. For each group of three characters, write
numbers underneath. Start at the right, with 1, then
double it (2) and write that below the middle digit then double that (4) and write it below the leftmost digit. Example:
011 010 111
421 421 421
Now
multiply the top by the bottom for each digit, i.e.
011 010 111
421 421 421
021 020 421
Next, go along the
bottom line, adding together the groups of three numbers:
021 020 021
0 + 2 + 1 = 3
0 + 2 + 0 = 2
4 + 2 + 1 = 7
3 2 7
These are the
octal numbers for the little groups of three
binary digits. Now, if we squash them into one long number:
327
And there we have it; 11010111 Binary = 327 Octal
If you don't understand this, I'd check out my Binary to Hexadecimal node. It has better examples.