City N has five-digit phone numbers. What is the largest number of subscribers that telephone

| June 11, 2021 | education

City N has five-digit phone numbers. What is the largest number of subscribers that telephone exchanges can serve if the number can start with 1, 2, 5 or 6?

For five-digit numbers that start with one, all possible variants of numbers can be from 10,000 to 19999. There will be 10,000 such numbers in total.

For five-digit numbers that start with a two, all possible variants of numbers can be from 20,000 to 29999. There will be 10,000 such numbers in total.

For five-digit numbers that start with a five, all possible variants of numbers can be from 50,000 to 59999. There will be 10,000 such numbers in total.

For five-digit numbers that start with a six, all possible variants of numbers can be from 60,000 to 69999. There will be 10,000 such numbers in total.

Thus, the answer is: 10,000 + 10,000 + 10,000 + 10,000 = 40,000 subscribers.



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