Doe my computer have magical RAM?

My Lenovo laptop has 2gb chip in one slot with the other empty. I'm running windows 7. Why does the properties window show that i have 4gb memory with 3.89 usable? Is there memory built into the board or somthing?

Swap perhaps? You are using some of your hard drive memory as ram?

Or there could be another slot for RAM on underside of MB or KB. With just "Lenovo laptop" and no model number from you, have to guess.

Some machines have slots in different places so you can't see the first slot.