Answer to Question #293419 in Discrete Mathematics for Tege

Question

how many possible telephone numbers are there when there are seven digits the first two of which between 2 and 9 inclusive the third digit between 1 and 9 inclusive and each of the remaining may be between 0 and 9 inclusive ?

Answer 1

There are 8 possabilities for each of the first two numbers, 9 possabilities for the third number and 10 possabilities for each of the remaining four numbers. So, there are totally

$8*8*9*10*10*10*10=8^2*9*10^4=5760000$ phone numbers