Commodore PET - Page 227

The finished program appears as follows:
l t1 PF: 1 t·n" ::J+::+::+:f'1UL TI PLE 1 t-iTE(;ER SUBTF.:ACT 1 ON:+::+::+:" : PR 1 NT
15 ZERO$= "0~~100tn~e:1e:10e:10e:1e:1000"
.:;::0 INPUT A$ .. B$
25 IF VAL(A$)=VAL(B$) THEN C$="0":GOTO 1190
30 IF VAL(A$»VAL(B$) GOTO 1000
40 X$=A$:A$=B$:B$=X$
50 8=1
1000 ~·::=LEt·~(A$): 'T'=LEt·j(B$)
1002 IF X>Y THEN F=X/2:GOTO 1006
.1004 F='T'/2
1006 IF F>INT(F) THEN F=INTcF)+l
1010 IF X(=F THEN AH=0:AL=VAL(A$):(;OTO 1040
1020 AH=VAL(LEFT$(A$.X-F»
1030 AL=VAL(RIGHT$(A$.F»
1040 IF Y(=F THEN B=0:BL=VAL(B$):(;OTO 1070
1050 BH=VAL(LEFT$(B$.Y-F»
1060 BL=VALCRIGHT$CB$,F»
1070 IF AL>=BL GOTO 1100
H180 AL=AL+10-tF
.1090
AH=AH-l
1100 CL$=STR$(INTCAL-BL»
1101
CL$=MID$(CL$.2,LEN(CL$)-1)
1102 CL$=LEFT$(ZERO$,F-LEN(CL$»+CL$
1110 CH$=STR$(INT(AH-BH»
1111
CH$=MID$(CH$,2,LEN(CH$)-1)
.1120 C$=CH$+CL$
1130 FOR 1=1 TO LEN(C$)
1140 IF VAL(MID$(C$,1,1»=0 THEN L=L+l
1150 IF VALCLEFT$CC$,I»(>0 THEN I=LEN(C$)
.1160 NE::·::T 1
1170 C$=RIGHT$(C$,LEN(C$)-L)
1180 IF :::;=1 THEt·~ C$="-"+C$
1190 PF: 1 tH : PF: 1 rH" AN:::;I·JER= ".; C$ : PR 1 NT
1200 A$="":B$="":C$="":CH$="":CL$=""
.1205 AH=0:AL=0:BH=0:BL=0F=0:8=0:X=0:Y=0
.1210 GOTO 2t1
1220 Et·jD
... :+:MULTIPLE INTE(;ER SUBTRACTION:+::+::+:
.-;- 123456789012
?757943572
ANSWER= 123398845440
?1234567890123456
7757943572
ANSWER= 1234567832179884
?9999999999999999
?71234567890
ANSWER= 9999998765432109
214