>>606
1! = 0!*1 = 1*1 = 1
2! = 1!*2 = 1*2 = 2
3! = 2!*3 = 2*3 = 6
4! = 3!*4 = 6*4 = 24
  :
n! = (n-1)! * n

k = 1
do 10 n=1, 10
k = n * k
write(*,*) 'n = ',n, ', n! =', k
10 continue
end