If I buy at 100:1 leverage 1 million USD and it goes against me 3 or 4 cents in a hurry, is there an exact formula to determine how much money I need to cover my position if I wait it out on and above my margin deposit for the 1 million which must be $10,000 more or less?

I am not worried at the moment how bad my strategy would be by holding on, I just want to determine the formula so I know exactly how much funds I need at all times to cover any position.

The ECN I was looking at doesn't close a position if my equity runs to zero, so I want to make absolutely sure I know how much I need for any fall against me.