According to the data you gave, that is, the opening price = 1000, the trading unit = 10 ton/lot, the number of positions opened = 10 lot, and the margin ratio =6%, then:

1, opening margin = opening price× marketing unit× opening quantity× margin ratio =1000×10× 6% = 6000 yuan.

After falling to 900, all positions are closed, that is, the closing price =900 and the number of positions closed = 10.

2. Closing loss = | closing price-opening price |× trading unit× closing hand = | 900-1000 |×10 =10000 yuan.

If you invested 65,438+million, there are still 90,000 left.

Note: you don't need to multiply the margin ratio when calculating the profit and loss.