The answer is the sum of the digits in 100!

Eg 10! is 3628800, and the sum is

3 + 6 + 2 + 8 + 8 + 0 + 0
## [1] 27

Solution is simple - unless we want to calculate everything on our own. Load gmp to handle lage numbers. Coerce 100 to bigz, calculate the factorial, coerce to text, split in individual characters, unlist, coerce to numeric and sum

library(gmp)
library(tidyverse)

answer <- 100 %>% 
  as.bigz() %>% 
  factorial  %>% 
  as.character() %>% 
  strsplit("") %>% 
  unlist() %>% 
  as.numeric() %>% 
  sum()