Q. 29. Write a FORTRAN program that goes on reading
values for an integer variable N until the value read
is zero or negative. For each positive value of N
read, the program tests whether N is a prime number
or not. Also it should print appropriate message.
(Dec. 2001)
Solution.
INTEGER N, I, J, K, L
WRITE (*, 10)
10 FORMAT(1X, 'ENTER VALUE
OF N = ',\)
READ (*, 11) N
11 FORMAT(I3)
100 IF (N .LE. 0) THEN GOTO 200
K = 0
I = 2
20 IF (I .GT. N/2) THEN GOTO 40
IF (MOD (N, I) .NE. 0) THEN
WRITE (*, 30) N
30 FORMAT(1X, 'I3 IS NOT A
PRIME NUMBER')
GOTO 150
ENDIF
I = I + 1
GOTO 20
40 WRITE (*, 50) N
50 FORMAT(1X, 'I3 IS A PRIME
NUMBER')
150 WRITE (*, 55)
55 FORMAT(1X, 'ENTER VALUE
OF N = ',\)
READ (*, 60) N
60 FORMAT(I3)
GOTO 100
200 STOP
END
Q. 30. Write a FORTRAN program which finds all prime
numbers between 1000 and 9999. (June
2000)
Solution.
INTEGER N, K, M
5 DO 20 N = 1000, 9999
K = 2
M = SQRT (N)
10 IF (MOD (N, K) .EQ. 0) GOTO 5
K = K + 1
IF (K .LE. M) THEN GOTO 10
WRITE (*, 15) N
15 FORMAT(1X, I5, 'IS A PRIME
NUMBER')
20 CONTINUE
STOP
END
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