QBASIC PROGRAM TO CHECK WHETHER A NUMBER IS PRIME OR NOT

CLS
 INPUT ENTER ANY NUMBER; N
 C = 0
 FOR I = 1 TO N
 IF N MOD I = 0 THEN C = C + 1
 NEXT I
 IF C = 2 THEN
 PRINT N; IS PRIME NUMBER
 ELSE
 PRINT N; IS NOT PRIME NUMBER
 END IF
 END

USING SUB

DECLARE SUB PRIME(N)
 CLS
 INPUT ENTER ANY NUMBER; N
 CALL PRIME(N)
 END
 
 SUB PRIME(N)
 C = 0
 FOR I = 1 TO N
 IF N MOD I = 0 THEN C = C + 1
 NEXT I
 IF C = 2 THEN
 PRINT N; IS PRIME NUMBER
 ELSE
 PRINT N; IS NOT PRIME NUMBER
 END IF
 END SUB

USING FUNCTION

DECLARE FUNCTION PRIME$(N)
 CLS
 INPUT ENTER ANY NUMBER; N
 PRINT N;
 END
 
 FUNCTION PRIME$(N)
 C = 0
 FOR I = 1 TO N
 IF N MOD I = 0 THEN C = C + 1
 NEXT I
 IF C = 2 THEN
 PRIME$="IS PRIME NUMBER"
 ELSE
 PRIME$="IS NOT PRIME NUMBER"
 END IF
 END FUNCTION