  100	for x = 1 to 20
  110	gosub 1000
  120	print x, 'factorial = ', y
  125	next x
  130	stop
 1000	if x > 1 then goto 1100
 1010	y = 1
 1020	return
 1100	x = x-1
 1110	gosub 1000
 1120	x = x+1
 1130	y = y*x
 1140	return
 1150	end
