Here I will show you a simple way of converting Binary to Hexadecimal, I will base this example on the first octet of an ip address.
Firstly I want you to understand that we need to break our 8 digit binary number up in to 2 sections. Each section is called a nibble. In this example we will be using 8 bit binary as you would see in an ip address.
Remember that with Hexadecimal once we count to the number "9" we then start on letters like so

• 1 2 3 4 5 6 7 8 9 A B C D E F

Lets use the Binary number 10001111 and convert it to Hexadecimal.
Binary number = 10001111
Break down in to 2 nibbles ( Groups of 4 ) from left to right 1000 1111
for the rest of this tutorial refer to my table below. You will see that I started with the first nibble which was "1000" I then took the last bit which is "0" and placed it in the column under number "1" I then took the 3rd bit which was "0" and placed it in the next column which is under number "2" I then took the 2nd bit of the nibble which is also "0" and I placed it in the next column to the left under number "4" I then took the 1st bit which is number "1" and placed it in the next column to the left under number "8"
I followed exactly the same procedure for the second nibble as you can see in the table below.
I then added all the 1s together for the 1st nibble as you can see in my table.

You will notice the second nibble totals 15 which is represented by the letter F

A = 10

B = 11

C = 12

D = 13

E = 14

F = 15 Answer = 8F