100 def fna(a)
110 ? a
120 for y = 0 to 10 : a = a * 2 : next
130 gosub 230
140 fna = 23 * a
150 fnend
160 ? x
170 input "x? "; x
180 gosub 200
190 goto 220
200 ? fna(x), x
210 return
220 end
230 return