Factorial/fækˈtɔːriəl/ Definition 1 of 2Pro Tip 1/3Math Specific Used mostly in math, particularly in probability and combinatorics. To solve this problem, you'll need to find the factorial of 7. Pro Tip 2/3Symbol Representation The exclamation mark (!) denotes factorial, like in 5! for 5 factorial. Can you calculate 8! for me? Pro Tip 3/3Non-Negative Integers Factorials are only defined for non-negative integers, and 0! is 1. Remember that the factorial of a negative number doesn't exist.