How long will it take me to earn enoughmoney for an Iphone 5s?

I currently have earned $4.50 I obviously have a long ways to go but anyways I make about $10 a week and I have to put 1/2 in my allowance so many weeks would it take for me to get enough money for the Iphone 5s

Added (1). sorry if this is in the wrong section

The lowest price for iPhone 5s is currently $199, which means that you will need to save up for forty (40) weeks.

The math:
199 rounded to 200
200 divided by 10 = 20
*Get half of that every week, so you need to double the time
=40 weeks

The priciest and the iPhone 5s with the most storage currently costs $399, which means that you will have to save for eighty weeks (80) to get it.

The math:
399 rounded to 400
400 divided by 10 = 40
*Get half of that every week, so you need to double the time
=80 weeks

Mind you, these are not including wireless carriers.

Mathematically, it would take you at least forty (40) weeks to get the iPhone 5s.