Residual income can have two different definitions or applications. The first definition, a less common application of residual income, is the money that is left after monthly debts are paid. This calculation is particularly important when a person is seeking financing or a loan based on their income and available money to cover the additional debt. In this scenario, the residual income is calculated by this formula:
Of course, there are large fast-food, pet store, and other enterprises that cost a great deal. However, consider a DVD rental machine, soda, or gum ball machines as more passive avenues to income. These require little maintenance, coins, bills, or revenue collected via credit cards, as well as periodic refilling of machines.  These machines are, perhaps, one of the more lucrative paths to a passive income with little input from you.
You can find dividend stocks using Google Finance Stock Screener which is free to use. Set the search criteria for the P/E Ratio, and Dividend yield (shown as a percentage) criteria. You can set minimum and maximum values; in the dividend yield box, set it between 2 and 100. This will search for stocks that pay dividends worth between 2-100% of the current stock price.

Now that you’ve chosen your market, find a way to start sharing your message, whether it’s a blog or podcast or Youtube channel, or whatever platform makes the most sense for your target market. Flynn says this is where you’ll start to build a fan base — and collect subscriber emails. You don’t need to get the whole world to follow you to make this work out financially. Wired cofounder Kevin Kelly wrote an article about 1,000 True Fans, which basically says that if you have 1,000 people paying you $100 a year, that’s a $100,000 a year. “You don’t need to serve everybody,”  says Flynn.

In equity valuation, residual income represents an economic earnings stream and valuation method for estimating the intrinsic value of a company's common stock. The residual income valuation model values a company as the sum of book value and the present value of expected future residual income. Residual income attempts to measure economic profit, which is the profit remaining after the deduction of opportunity costs for all sources of capital.