To take control of your money and become wealthy, follow personal finance rules like the Rule of 72 for estimating investment doubling time, age-based asset allocation, and the 50-30-20 budgeting rule. According to Ashish Aggarwal, MD, Acube Ventures, anything that expands at a compound rate, including the population, macroeconomic data, charges, or debts, may be subject to the Rule of 72. The economy is predicted to double in 72 / 4% = 18 years if the GDP expands at a rate of 4% per year.