To keep our financial, investment, tax, health, birthdays information and the like. We can use it for simple as well as specialized calculations. Like, comparing cost and returns of various loan, investment and insurance options available in the market.
Rent or mortgage, homeowners insurance or renters insurance, all utility bills, auto loan or auto insurance payments, gas for your vehicle, food for home, and so forth. Once again, these are items that you cannot live without.