A city has to accommodate for 9.99 million households requiring a telephone number. They are about to issue 8-digit telephone numbers, with 5 as the first digit.

How many different telephone numbers can be created if repetition of digits is allowed?

xxJenny1213xx Jan 29, 2021

#1**+1 **

first digit must be a 5 so the remaining 7 digits can be anything (0-9) but they all start with a 5

10^{7 }= 10,000,000 phone numbers

Guest Jan 29, 2021

#3**0 **

Why did you repeat your question?

The answer on your prior post is correct; this answer is not....

Guest Jan 29, 2021

#4**0 **

this is if the digit is allowed, the other question is if the digits are not allowed

xxJenny1213xx
Jan 29, 2021