10 REM PERFECT NUMBERS
   20 *TV 255,0
   30 MODE4
   40 VDU 19,0,4,0,0,0
   50 CLS
   60 PRINT"This program searches for perfect       numbers on the assumption that they     follow the same mathematical expression as the highest known perfect number."
   70 PRINT:PRINT"Whenever a perfect number is found it is printed on screen and to the printer   before continuing the search for the    next number."
   80 PRINT:PRINT"Be warned that the fifth perfect number will take quite some time to find.      Probably longer than 10 days !!":PRINT
   90 PRINT"Please prepare your printer..."
  100 PRINT:PRINT"...then press any key to continue."
  110 X=GET
  120 CLS
  130 PRINT:PRINT TAB(25,1) "COUNTER"
  140 J=0
  150 FOR N=1 TO 500
  160 IF J=20 THEN GOTO 300
  170 A%=(2^J)*((2^(J+1))-1)
  180 J=J+1
  190 X%=1
  200 M%=1
  210 M%=M%+1
  220 PRINT TAB(20,3) M%
  230 IF M%>A%/2+1 THEN GOTO 290
  240 IF X%>A% THEN GOTO 290
  250 B=A%/M%
  260 IF B=INT(B) THEN X%=X%+B ELSE GOTO 210
  270 IF B=2 THEN PRINT TAB(20,3) A% ELSE GOTO 210
  280 IF X%=A% THEN PROCperfect
  290 NEXT
  300 END
  310 DEF PROCperfect
  320 Z=Z+1
  330 VDU2:IF Z=1 PRINT TAB(0,5+Z)"I'M A PERFECT NUMBER ...",A%:VDU3
  340 VDU2:IF Z=2 PRINT TAB(0,5+Z)"...AND SO AM I       ...",A%:PRINT:VDU3
  350 VDU2:IF Z=2 PRINT TAB(0,7+Z)"PLEASE WAIT.ANOTHER WILL BE ALONG SOON.":PRINT:VDU3
  360 VDU2:IF Z=3 PRINT TAB(0,8+Z)"HERE I AM            ...",A%:PRINT:VDU3
  370 IF Z=3 THEN PROCtexta
  380 IF Z=4 THEN PROCtextb
  390 VDU2:IF Z>4 THEN PRINT "WAS IT WORTH THE WAIT  ...",A%:VDU3
  400 VDU3
  410 ENDPROC
  420 DEF PROCtexta
  430 VDU2:PRINT TAB(0,10+Z)"THERE'S NOT MANY OF US AROUND YOU KNOW."
  440 PRINT "YOU'LL NOW HAVE A SLIGHT WAIT BEFORE YOU SEE ANOTHER ONE(COUNTER=4100 approx).":PRINT:VDU3
  450 ENDPROC
  460 DEF PROCtextb
  470 VDU2:PRINT TAB(0,12+Z)"NOT TOO LONG A WAIT I HOPE ...",A%:PRINT
  480 PRINT "YOU'LL NOW HAVE A MUCH LONGER WAIT."
  490 PRINT "BE PREPARED TO LEAVE YOUR COMPUTER ON   ALL WEEK OR POSSIBLY EVEN LONGER!":PRINT
  500 PRINT "THE NEXT PERFECT NUMBER IS MUCH LARGER!!"
  510 ENDPROC