Need help with my sons maths home work

[gorby928]

Hi I need some help with my sons maths home work as I am useless.I just need to know how to work out the following question so I can help him if he gets stuck.I wont do it for him but I need to be able to help him.

2 Digit problem (year 3)

500 people on a planet,each person is about to get a phone.The phone company wants to work out how many digits to have in the phone numbers.

1,If they have 2 digits in each phone number will they get enough phone numbers for everyone ?

2,If they have 3 digits in each phone number will they get enough phone numbers for everyone ?

Thanks :?

 

[galactus]

Think a little. It's rather intuitive. How many people are there?. 500.

Is that a 3 digit or 2 digit number?.

 

[gorby928]

Sorry to be so thick,maths is not my strong point as you can guess,so is it really that simple,500 is a three digit number so the phone numbers must be three digit numbers as well ? as in tens and hundreds ?Theres nothing more to it ? and thank you for the quick reply.

 

[Deleted member 4993]

What more could be there?

 

[gorby928]

I know I just look at numbers and I tend to worry myself into a bit of a tizz,thanks once again.

 

[johnnycal96]

it must be a 3 digit number between 100 to 999 as the whole range can be taken by 500 people.

 

[Denis]

it must be a 3 digit number between 100 to 999 as the whole range can be taken by 500 people.

Disagree Johnny.
The answers to the 2 specific questions are:

1,If they have 2 digits in each phone number will they get enough phone numbers for everyone ?

Answer: no ; 10 to 99 will cover 90 people

2,If they have 3 digits in each phone number will they get enough phone numbers for everyone ?

Answer: yes ; 100 to 999 will cover 900 people

But it doesn't have to be all 3 digit numbers; 90 2-digit, 410 3-digit will do.