Random Function in Autoit

[Daywap 0]

That's my code:

#Include <FF.au3>

$test = Random(1000,18000)

_FFConnect()

_FFOpenURL("http://google.com/String($test)")

How to make it work? I tried with .' or ". and I can't make. Any help would be great.

[JohnOne 1,541]

_FFOpenURL("http://google.com/" & String($test))