telephone number possibilities

[nancygaye]

I have no idea how to approach this problem:

A phone number consists of seven digits, the first 3 are the exchange. How many different phone numbers are possible within the 537 exchange?

Thanks in advance.
nancy

 

[pka]

A phone number consists of seven digits, the first 3 are the exchange. How many different phone numbers are possible within the 537 exchange?

(10)(10)(10)(10)=10<SUP>4</SUP>

 

[nancygaye]

to PKA

and, I certainly don't!

Can you explain?

 

[stapel]

Re: to PKA

and, I certainly don't! Can you explain?

Are you referring to the quote in pka's signature? If so, then try Googling "binary numbers" to find lessons on this topic. If not, please clarify.

Thank you.

Eliz.

 

[nancygaye]

I am referring to his answer to my post about the phone number possibilities.

My original question was:

A phone number consists of seven digits, the first 3 are the exchange. How many different phone numbers are possible within the 537 exchange?

PKA's answer:

(10)(10)(10)(10)=10 (4 power)

and yes, part of the answer was the quote about binary numbers.

I would like to know how he derived the answer so I will understand for future problems.

Thanks.

 

[pka]

In the telephone exchange 537 the first three numbers are fixed.
The last four numbers can be any one of ten digits.
Thus we have numbers in that exchange 537-_ _ _ _.
Each of the four blanks can be filled by any one of ten digits.
Thus 10<SUP>4</SUP>.

 

[nancygaye]

Thanks for the explanation.

nancy

 

[Denis]

or simply all the numbers from 1 to 9999:
537-0000, 537-0001 .... 537-9998, 537-9999

1 to 9999 = 10000 numbers = 10^4