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Q: When were 3 digit operator assisted telephone numbers used?
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Continue Learning about Math & Arithmetic

What is the number of 5 digit telephone numbers having atleast one of their digits repeated?

5 digit telephone numbers having at least one of their digits repeated is = total possible 5 digit telephone numbers - 5 digit telephone numbers without any digit being repeated. =(10*10*10*10*10)-(10*9*8*7*6) =100000-30240 =69760


How many 7 digit telephone numbers can be formed the first digit cannot be zero?

9,000,000 if there are no other requirements.


How many different 7-digit telephone members are possible if the first digit can not be zero and no digit repeat?

There are 10 possible numbers that can be chosen. Since the first digit can't be 0, there are 9 selections for the first digit. The second number can include a 0, but can't include the first number chosen, so there are 9 selections for the second digit. Then there are 8 digits for the next number, 7 digits for the next number, and so on. Total telephone numbers are: 9*9*8*7*6*5*4 = 544320 phone numbers.


How many seven digit telephone numbers are possible if the first number is not allowed to be 0 or 1?

8,000,000 million telephone numbers are possible with these conditions, corresponding to the numbers 2,000,000 - 9,999,999. Many countries have forced dialing of the area code now, creating telephone numbers with a minimum of 10 digits. This means there are 8 million possible telephone numbers in each area code. (area code of 3 digits long).


How do 3 digit numbers compare to 4 digit numbers?

3 digit numbers are lessthan 4 digit numbers