The scope of a function

[ack3439]

i have a function that changes a root variable that i pass into it. the problem is that the changes to the variable are only present in the function, once the function ends the new value disappears as well. here is a simple example of what i'm talking about:

//there's the variable i want to manipulate
fakeVar=100;

function mult(whichVar){
//let's multiple the variable by 2.
	whichVar*=2;
        trace(whichVar) // traces 200...correct.
        trace(fakeVar) //traces 100, the original value, not correct
}

box.onRelease=function(){
//call the function with the variable i want to update.
	mult(fakeVar)
}

the function changes the variable within its own scope, but is there a way for it to change the variable outside of its own scope as well? In my real code, the code within the function is in an onEnterFrame event, so i need it to update the variable every frame....