To Access blocked sites: Use Decimal Address

Many times both Domain Name & IP Address are banned, Use Decimal Address to Access that Website

This unique Mathematics based trick will probably work when websites are blocked in your institution or corporate network based on the host name or their IP address.
The trick is to convert the human readable website address that's blocked (like http://www.facebook.com/) into an IP address (66.220.147.44) and again translate this value to a decimal address which is probably not blocked by the website filters.
Here's a step by step guide to render http://www.facebook.com/ to a decimal address:

How to Access Restricted Websites
1) get its IP address (66.220.147.44), by pinging the name (if you have a direct internet connection) or if you only have access via a web proxy then find it out by using a networking website like network-tools. com.

2) start your PC's calculator, and change it to scientific mode (using the "View" menu)
3) enter each of the four IP octets, one by one, converting them to binary (enter number and click on the "Bin" radio button)
Thus 216.178.39.74 becomes
66 = 1000010
220 = 11011100
147 = 10010011
44 = 101100

Notice how any binary numbers less than 8 digits long have had leading zeroes added to pad them out. Reassembled into IP address order, you get 1000010.11011100.10010011.101100
4) Remove the dots, so you get one huge line of binary, thus: 10000101101110010010011101100
5) Copy this binary string
6) Click on the "Dec" button on your calculator, and you will get the converted value of 280437996

7) Add the hypertext protocol prefix and paste into your browser's address bar: http://280437996

 

Source : Ganesh Ghube's Blog