10 INPUT"NUMBER IN HEX";HX$
20 L=LEN(HX$)
30 IF LEFT$(HX$,1)="$"THENHX$=RIGHT$(HX$,L-1):L=L-1
40 IFL>4THEN 10
50 IFL<4THEN HX$="0"+HX$:L=L+1:GOTO50
60 FORA=1TO4:D=ASC(MID$(HX$,A,1))-48
70 IFD>9THEND=D-7:IF D>15THENPRINT"NUMBER ERROR":GOTO10
80 DEC=DEC*16+D:NEXT
90 PRINTDEC