The "101st Number" typically refers to the number 101 in a sequence or list. In mathematics, it is an odd number and is often used in various counting systems. It is also the first three-digit prime number, meaning it can only be divided by 1 and itself without leaving a remainder. In popular culture, the term "101" is often used to denote an introductory level of knowledge about a subject, such as in college courses or tutorials. For example, "Psychology 101" would be an introductory course in psychology, providing foundational concepts for students.