Can someone please show me how to do the calculation ? Thanks.

NP. 10 contracts right? The numbers they give you are all for 1 contract, so just do the math as if its 1 contract, then at the end x 10. Initial margin is $5, Maintenance is $3, the trick is once you dip below maintenance margin, you have to deposit back up to Initial. At Day 0 your fine, you enter your short. At Day 1 the settlement is $103, moved against you $3. Your Initial margin decreases to $5-3= 2 and you must redeposit up to initial. At Day 2, you profit because it went from $103-96 = $7 gain for you, your margin is now $5 + $7 = 12 At Daty 3, you loose $2, and your end with margin of $10, you had 10 contracts so X 10 = $100

Thanks you so much Matt !

no problem