10 REM FACTORIAL
20 REM COMMODORE BASIC 2.0
30 INPUT "N=";N: GOSUB 100
40 PRINT N;"! =";F
50 GOTO 30
100 REM FACTORIAL CALC USING SIMPLE LOOP
110 F = 1
120 FOR I=1 TO N
130   F = F*I
140 NEXT
150 RETURN