I found this question in Tanenbaun's book of Computer Networks.
"How many end office codes were there pre-1984, when each end office was named by its three-digit area code and the first three digits of the local number?Area Codes started with a digit in the range 2-9, had a 0 and 1 as the second digit, and ended with any digit. The first two digits of a local number were always in the range 2-9. The third digit could be any digit. "
I don't think I even understand the question; therefore, I would appreciate any kind of help
2007-01-21 10:08:29 · 2 answers · asked by petre 1 in Computers & Internet ➔ Computer Networking
Its really quite simple, for example an area code could be 602 but not 134 because the first digit must be 2-9 and the second digit must be 0 or 1. So the number of possible area codes were 8 X 2 X 10 = 160.
Similarly for the first 3 digits of the local number also called the "exchange" you have 8 X 8 X 10 = 640 possibilities.
2007-01-21 10:24:08 · answer #1 · answered by rscanner 6 · 1⤊ 0⤋
Tanenbaum Networking Book
2017-01-14 08:51:42 · answer #2 · answered by ? 4 · 0⤊ 0⤋
Linksys Wireless Routers.
2016-03-14 21:43:47 · answer #3 · answered by Anonymous · 0⤊ 0⤋