You have sold short 40 shares of company LOL at $82. Your initial margin is 50% and your maintenance margin is 30%. A few weeks later, just after the company paid $2 dividends, you hit the maintenance margin (exactly) and receive a margin call. How much money do you have to add to your account to bring the margin back to the initial level?

You have put down $600 and borrowed $400 in order to purchase 20 shares in a company trading at $50 per share. The next day the share price drops unexpectedly to $32. How many shares do you have to sell (in order to pay down part of your loan) to restore the percentage margin to 60%?