The Rule of 72

Everyone should know this basic investment rule. No excuse for saying that my school teacher never taught me this.
Rule of 72 is to help you estimates the amount of time to double your money.

72 / Interest rate = Years to double the money

For instances:
1. If your have $10K in wws2020/unit trust which give you return at 10% every year. 72/10=7.2 which means your money will double to become $20K in 7.2 years.

2. If inflation rates reported at 3% averagely. 72/3=24 which means your money will lose half of its value in approx. 24 years. If you are planning to retire with $1mil, you need to take the inflation into the calculation because 1mil today = 500K 24 years later. Now adjust your target to $2mil if you want to have $1mil worth Quality of Life (QoL) in 24 years later.