I can't grasp the underlying process on how this is working. n/2(f+l) = algorithm sum of all integers n= number of all integers f= first integer l= last integer Example: 1, 2, 3, 4 4/2(1+4) 2(5) = 10 I know how to do it, but I don't really understand how to actually do it. Am I just too stupid? Why do I need to split the sum of all integers? Why am I adding the first + last integer? Why when I times them together does it work? How did he create the algorithm for this?