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30 lines
821 B
Plaintext
30 lines
821 B
Plaintext
10 text : home
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20 print "Prime numbers"
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30 print " ";
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40 for x = 1 to 1000
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50 gosub 1000
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60 if p == 1 then print x;" ";
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70 next
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80 print
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90 end
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1000 rem ** subroutine to check for prime **
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1010 rem number to be checked is stored in x
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1020 rem d is used for divisor
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1030 rem q is used for quotient
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1040 rem p is used for return value, if x is prime, p will be 1, else 0
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1050 p = 0
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1060 if x < 2 OR x <> int(x) goto 1180
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1070 if x == 2 OR x == 3 OR x == 5 then p=1 : goto 1180
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1080 if x/2 == int(x/2) goto 1180
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1090 if x/3 == int(x/3) goto 1180
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1100 d = 5
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1110 q = x/d : if q == int(q) goto 1180
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1120 d = d + 2
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1130 if d*d> x goto 1170
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1140 q = x/d : if q == int(q) goto 1180
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1150 d = d + 4
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1160 if d*d <= x goto 1110
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1170 p = 1
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1180 return
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1190 rem ** end of subroutine to check for prime **
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