factorial
🇺🇸
/fækˈtɔːriəl/
🇬🇧
/fækˈtɔːriəl/
A factorial is the product of all positive integers less than or equal to a given positive integer.
The number 5 factorial, written as 5!, equals 120 because 5 times 4 times 3 times 2 times 1 equals 120.
5的阶乘,写作5!,等于120,因为5乘以4乘以3乘以2乘以1等于120。