Try using a binary countoff
I believe it can be used to isolate a specific byte by breaking the number down.
Like for the examples you posted, 263 - 256 = 7, 519 - 512 = 7
EDIT:
Actually, it wouldn't be binary, because that wouldn't tell you exactly what it is, you would need to do base 16.
Here's a table of numbers. By trying to subtract each of them starting with the highest, you can tell exactly what hex value is in each place.
These are the numbers you will need to subtract. It goes up to 16^7
QUOTE
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16