The price of Apple stock is currently $118.3 and you decide to sell short 400 shares. The initial margin is 60%.

If the broker's maintenance margin is 50%, and the stock price now rises to $129.19, you are now getting a margin call. One method (the other method is to add some cash into the account) to lift your percentage margin back to the maintenance level is to reduce some debt (i.e., short cover, either by you or the broker). Find the number of shares (keep the decimals for now) you must purchase in the market & pay back?