The offsets use the hexadecimal (base 16) numbering system. While the decimal (base 10) numbering system goes from 0-9 (10 single digit numbers) before reaching 10, hexidecimal goes like this:
0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,10,11,etc.
That is 16 single digit numbers (the letters represent numbers btw) from 0-F, as opposed to decimal's 10.
So the number 2F in hex (short for hexadecimal) is 47 in decimal.
The windows calculator program can convert between hexadecimal, decimal, octal (base 8), and binary (base 2), when put into scientific mode (found under view). Just insert a number for a certain numbering system and then switch the numbering system and the number should change to fit it.