3

 
 
  
  #3. Sum of n Natural Numbers 
------------------------------
num = int(input(“Enter value of n: ”))

if num < 0:
   print("Enter a positive number")
else:
   sum = 0
   # use while loop to iterate until zero
   while(num > 0):
       sum += num
       num -= 1
   print("The sum is", sum)


OUTPUT
--------------------

Enter value of n: 3
The sum is 6

Enter value of n: 5
The sum is 15