Yeast Question - Starters

Ok,
I just made a starter and am wondering how many yest cells this is going to reproduce. I made a 1800ml starter and am going to pitch in a Wyeast American Ale Activator pack into it an use a stir plate. The Activator says it has 100 billion cells. I understand a stir plate can up the number of cells created by the starter by up to 4 times. So off of an 1800ml starter, how many yeast cells can I expect to reproduce?

I'm hoping that it will be enough for me to take about 250ml off of the starter to store for future use and give me plenty for the 10 gallon batch I plan on brewing up on Sunday.

Thoughts, opinions, criticisms, pointless observations?

TIA

I would pitch the whole thing. then you can get the yeast back off of the trub in the primary when it's done fermenting. It will also yield healthier yeast