Imagine you want to buy 100 shares of Apple Computer, Inc. (Symbol: AAPL). The current market price is $53.95. You log into your brokerage account or call your broker directly on the phone and tell him, “Place a market order for 100 shares of Apple Computer, ticker symbol AAPL”. By the time the order is actually executed a few seconds later, the market price may be higher or lower; $54.10 or $53.75 for example. Your cost before commissions will vary accordingly. In our example, the difference between $5,410 for the round lot and $5,375, or $35. That may not seem like much, but thanks to the time value of money, those savings can result in a substantially larger nest egg.