Julia Kagan is a financial/consumer journalist and former senior editor, personal finance, of Investopedia. A Social Security number (SSN) is a numerical ID for U.S. citizens and residents to track ...

Carla Tardi is a technical editor and digital content producer with 25+ years of experience at top-tier investment banks and money-management firms. Eric's career includes extensive work in both ...

Abstract: In probability theory the expected value of functions of random variables plays a fundamental role in defining the basic characteristic measures of probability distributions. For example, ...