The factorial of 100 is 9.3326215443944E+157 or approximately 9.332622e+157. This number is too large to be calculated manually and is often represented as an exponential. The number of trailing zeros in 100! is 24. The number of digits in 100 factorial is 158. The factorial of 100 is calculated by multiplying all positive integers less than or equal to 100. The formula for calculating the factorial of a number n is n! = n x (n-1) x (n-2) x ... x 3 x 2 x 1.