what is factorial

Factorial is a mathematical function denoted by the symbol "!". It is used to find how many ways things can be arranged or the ordered set of numbers. The factorial of a non-negative integer n is the product of all positive integers less than or equal to n. For example, 4! (read as "four factorial") is equal to 4 x 3 x 2 x 1, which is equal to 24. The factorial of 0 is defined to be 1. The factorial function is used in many mathematical concepts such as probability, permutations and combinations, sequences and series, etc. . The factorial number system is a mixed radix notation for numbers in which the place values of each digit are factorials. The factorial function is a common feature in scientific calculators and is included in scientific programming libraries such as the Python mathematical functions module and the Boost C++ library.