10 LET N$="0"
 20 SCROLL
 30 PRINT N$
 40 LET L=LEN N$
 50 LET N=VAL N$(L)+1
 60 IF N=8 THEN GOTO 90
 70 LET N$(L)=STR$ N
 80 GOTO 20
 90 LET N$(L)="0"
100 IF L=1 THEN GOTO 130
110 LET L=L-1
120 GOTO 50
130 LET N$="1"+N$
140 GOTO 20