A speculator starts with HK$80,000 (~US$10,000) of capital.
He can buy one Hang Seng Index futures contract (HSIF Contract), which requires a HK$80,000 margin.
Using his unique trading strategy, he makes a profit of HK$3,000 a day or HK$60,000 a month (HK$3,000 x 20 days). That HK$60,000 profit is represented by a silver coin.
In Month #01, he gains a silver coin.
In Month #02, he gains another silver coin.
At the end of Month #02, he has accumulated HK$200,000 (two silver coins + his initial capital) in his account.
In Month #03, he buys two futures contracts that bring him two more silver coins.
At the end of Month #03, he has HK$320,000 (two extra silver coins + HK$200,000 from previous month) in his account.
In Month #04, he can buy four futures contracts and he gains four silver coins.