10 REM *** WRITTEN BY DAVID AHL, DIGITAL
20 PRINT "BOOMERANG PUZZLE FROM ARITHMETICA OF NICOMACHUS -- A.D. 90!"
30 PRINT :PRINT "PLEASE THINK OF A NUMBER BETWEEN 1 AND 100.":PRINT 
40 PRINT "GOT IT?     O.K. LET'S START....."
50 PRINT "YOUR NUMBER DIVIDED BY 3 HAS A REMAINDER OF";:INPUT A
60 PRINT "YOUR NUMBER DIVIDED BY 5 HAS A REMAINDER OF";:INPUT B
70 PRINT "YOUR NUMBER DIVIDED BY 7 HAS A REMAINDER OF";:INPUT C
80 PRINT :PRINT "LET ME THINK A MOMENT":D=70*A+21*B+15*C
85 FOR I=1 TO 1000:IF A*B*C=105 THEN 90 :NEXT I
90 IF D<=105 THEN 110 :D=D-105:GO TO 90 
110 PRINT :PRINT "YOUR NUMBER WAS",D,", RIGHT";:INPUT A$:PRINT 
120 IF A$="YES" THEN 150 :IF A$="NO" THEN 160 
140 PRINT "EH?  I DON'T UNDERSTAND '",A$,"'.  TRY 'YES' OR 'NO'.":GO TO 110 
150 PRINT "HOW ABOUT THAT!!":GO TO 170 
160 PRINT "I FEAR YOUR ARITHMETIC IS IN ERROR."
170 PRINT :PRINT :PRINT :PRINT "LET'S TRY ANOTHER.":GO TO 30 :END