Question

what is factorial(!)? how do you solve its sum?

Answer 1

factorial means multiplication of of that number with every before number till 1 means if its 5!  then it means 5*4*3*2*1=120
10!=10*9*8*7*6*5*4*3*2*1=3628800

Answer 2

Factorial means the product of the given integer and all smaller integers in an descending order. Its symbol is an exclamation mark(!). For example: 6! = 6 * 5 * 4 * 3 * 2 * 1 = 720