Variable with variable name

Hi I’m wondering how do u call a variable that has a variable name.

[AS]
max = 10;

For (i=1; i<=max; i++)
{
this.attachMovie(“expBall”, “ball”+i, i);
};

[/AS]

Now I want
ball1._x = 100i;
ball2._x = 100
i;

until ball10._x=100*i;

how can i do that? how do i address a variable name which is variable?