lets assume the australian phone numbers 04xx xxx xxx are true for the question.
this means that there are 8 different positions for numbers to be assigned to and from 0-9 are the numbers available.
for the first number there are simply 9 options, AND (and= multiply the numbers), for the second number there are also 9 available numbers. So, 9x9.....x9, is the total phone number combinations where it is multiplied by itself 8 times (since that is the amount of different positions).
so the answer is 9x9x9x9x9x9x9x9, or simply, 98=43046721
Hopefully this is right, haven't done this since last year
