00:02
All right, so a nice little counting problem.
00:04
All right, so we have a country that's a three -digit area code.
00:08
How many area codes are possible with this arrangement? so let's read the arrangement a little more carefully.
00:14
So we've got three spots.
00:18
So let's see.
00:21
I'll have a zero or one in the middle digit.
00:23
So there's two choices for the middle digit and do not have zero one as the first digit.
00:28
So there are eight choices, leaving 10 for the...
00:31
The last choice, multiply these together, we get 160.
00:36
If the country uses an eight digit sequence for each area code and how many telephone numbers does the country permit the first two digits follow the area code cannot be zero.
00:54
All right, so we've got eight digits.
00:56
One, two, three, four, five, six, seven, eight...