QBASIC PROGRAM TO CALCULATE SUM OF FIRST N NATURAL NUMBERS

 CLS
 INPUT “ENTER THE NUMBER”; N
 S = N * (N + 1) / 2
 PRINT “SUM OF”; N; “NUMBERS=”; S
 END

USING SUB

DECLARE SUB SUM(N)
 CLS
 INPUT “ENTER THE NUMBER”; N
 CALL SUM(N)
 END
 
 SUB SUM(N)
 S = N * (N + 1) / 2
 PRINT “SUM OF”; N; “NUMBERS=”; S
 END SUB