The factorial of a number n can be defined as the product of all positive integers that are greater than 0 but less than or equal to n. Almost every scientific calculator has a built in "factorial" function. This makes the really cumbersome process of multiplying each number relatively straight-forward. The TI-83 is on exception to this rule. As shown in the video, the factorial of any number can be found by simply typing the number and applying the built in "factorial" function. Since the results of this function are large numerically, trying to find a factorial of a large number will result in an overflow.