The telephone prefix for a university is 243. THe prefix is followed by four digits. How many telephones are possible before a new prefix is needed?
well, there are 10 choices for each digit, so ...
To find out how many telephones are possible before a new prefix is needed, we need to consider the number of available combinations for the four-digit portion of the telephone number.
Since each digit can range from 0-9 (10 possibilities), there are 10 choices for each of the four digits. Therefore, the total number of possible combinations is calculated by multiplying the number of choices together:
10 choices for the first digit * 10 choices for the second digit * 10 choices for the third digit * 10 choices for the fourth digit = 10^4 = 10,000.
So, before a new prefix is needed, there are 10,000 possible telephone numbers available.