Fun with Math and IP addresses. c 1999 By Steven Smiley [ssmiley@altavista.net] Have you ever received an email that listed the following: http://3509152108? Ever wonder what this number is? Before firing up your browser, ping the number and see what happens. In this case, ping(and other IP programs) returns the IP address 209.41.105.108. There's a simple formula that converts IP addresses into a nondotted-decimal format. Here's that formula: (A*256^3)+(B*256^2)+(C*256)+(D*1) Where 256^3 is 256 cubed, 256^2 is 256 squared. Each letter represents the octets of the IP address, starting from the left. So, now let turn our IP address into a decimal number. 209 41 105 108 A B C D (209*(256^3))+(41*(256^2))+(105*256)+(108*1) 209*(256^3) = 3506438144 41*(256^2) = 2686976 105*256 = 26880 108*1 = 108 Sum = 3509152108 The above number could be turned back into an IP address, by converting the number to binary, breaking the binary number down into 4 octets and then converting each octet into a dotted-decimal number.