How to display only four decimal places with actionscript 3.0

programming flash
1

Hi,
How can I tell flash to use only four decimal places when a number is display in a textField?
Something like this:

2.2356 , 0.2538, 0.2968, 0.0001 etc.

Instead of infinite numbers:

2.23565985… , 0.2538486…

Thanks a lot.