Editor's note: The following are questions received from listeners of "RealMoney Radio." To send Cramer a question about topics from his radio show, click here. Listen to Cramer's latest radio show by clicking here. Should investors only buy stocks in 100 share lots? -- Chris from Massachusetts James J. Cramer: It is absolutely not necessary to buy stocks in 100 share lots. Investors should be focused on the dollar amount being invested in a stock rather than the number of shares. If an investor has $1,000 to invest in a new position, I would rather see them buy 10 shares of a great $100 stock, than 100 shares of a mediocre $10 stock. Is it time to sell Merrill Lynch (MER)? -- Joe from Florida James J. Cramer: I would actually hang on to Merrill Lynch. The company isn't as loved or admired by the media as Goldman Sachs ( GS), but Stan O'Neal has done a phenomenal job of turning Merrill into a profit machine. I believe that Merrill's private client unit is top notch, and that their banking business has come a very long way in the past few years. Want more Cramer? Check out Jim's rules and commandments for investing from his latest book by clicking here.