Stumbling upon this blog post from one of the famous Financial Blogger from HKG (取之有道) Other than the famous “Rule of 72” which is well known by most of value investors , below are few more mathematical concept which I think is also rather important for anyone who is involving in stock investing. Concept explained : Rule of 72 ( by Investopedia ) The 'Rule of 72' is a simplified way to determine how long an investment will take to double, given a fixed annual rate of interest. By dividing 72 by the annual rate of return, investors can get a rough estimate of how many years it will take for the initial investment to duplicate itself. For example, the rule of 72 states that $1 invested at 10% would take 7.2 years ((72/10) = 7.2) to turn into $2. In reality, a 10% investment will take 7.3 years to double ((1.10^7.3 = 2)......