Python Program to Find the Sum of Natural Numbers

In this example, we will write a simple program to take input number from the user and calculate the sum of the natural numbers. To better understand this example, make sure you have knowledge of the following tutorials:-

• Python while Loop Statements
• Python if…else Statement

Python Program to Find the Sum of Natural Numbers

number = int(input("Enter a number: "))

if number < 0:
   print("Enter a positive number")
else:
   sum = 0
   while(number > 0):
       sum += number
       number -= 1
   print("The sum is",sum)

The output of the above program is:-

Program Explanation

The user provides the number up to which the sum needs to be generated.  The sum is initialized as 0 and while loop is used to update the sum with the addition of the number in each loop. The loop is maintained until the number is greater than 0 and finally, the sum is printed.

number = int(input("Enter a number: "))
sum = number * (number + 1) / 2
print("The sum is: ", sum)