Posted by angela on Thursday, May 13, 2010 at 8:11pm.
a 7 digit phone number has a 3 digit prefix followed by 4 digits.how many different phone numbers are possible??

math  Damon, Thursday, May 13, 2010 at 8:23pm
I assume 0 through 9 are allowed and repeats are possible. For example 0000000 is allowed.
How many prefixes?
10*10*10 = 1,000
how many digits
10*10*10*10 = 10,000
so 10^3 * 10^4 = 10^7 = 10 million
I guess that is why they needed area codes.

math  Kassen, Friday, January 1, 2016 at 10:37am
7!=1*2*3*4*5*6*7=... (combinatoric)
Answer This Question
Related Questions
 Math. Explain  From the digits 1, 2, 3, and 4, how many positive integers are ...
 math  The Gallup Poll uses a procedure called random digit dialing, which ...
 6 th grade Math  You can find the total number of different 4digit numbers of ...
 computer programming  Write a program that simulates the dial of a phone number...
 MATH Trouble  I have no idea what this problem means: For how many twodigit ...
 math  use the clues to find the 7th digit mystery number. * Its is between 1 ...
 Math  1.) A security code has seven characters. Each code begins with two ...
 MATH  Jason remembers nine digits of a ten digit phone number. He remembers ...
 Math (Reiny)  Regarding my question below, when the question talks about digits...
 4th grade math  Find the mystery number. It is a 4 digit odd number. All the ...
More Related Questions