**Natural Number:**

A natural number, as the name implies, is a number that occurs often and clearly in nature. It is a whole number with no negative digits.

Some mathematicians agree that a natural number must contain 0 while others do not. As a result, a list of natural numbers can be described as follows

N= 1 , 2 , 3 , 4 , 5 etc.

**Prerequisite:**

Explore more instances related to python concepts from Python Programming Examples Guide and get promoted from beginner to professional programmer level in Python Programming Language.

**Examples:**

**Example 1:**

**Input :**

number = 5

**Output:**

Sum of natural numbers till 5 = 15

**Example 2:**

**Input :**

number = 43

**Output:**

Sum of natural numbers till 43 = 946

## Program to Find the Sum of Natural Numbers in Python

Below are the ways to print the sum of natural numbers in python:

### Method #1:Using for loop

- Take a variable say
**sum**and initialize to 0 - Iterate from 1 to N using for loop and range() function.
- For each iteration add the iterater value to
**sum**. - Print the
**sum**.

**Below is the implementation:**

# given number number = 5 # Take a variable say sum and initialize to 0. sum = 0 # Iterate from 1 to number using for loop and range function for i in range(1, number+1): # add the iterater value to sum. sum = sum + i # print the sum print("Sum of natural numbers till", number, "=", sum)

**Output:**

Sum of natural numbers till 5 = 15

### Method #2:Using while loop

- Take a variable say
**sum**and initialize to 0 - The while loop was used to iterate until number became zero.
- In each loop iteration, we have added the number to
**sum**and decreased the value of number by 1. - Print the sum.

**Below is the implementation:**

# given number number = 5 # Take a variable say sum and initialize to 0. sum = 0 # iterate till the number becomes 0 using while loop while(number != 0): # add the number value to sum sum = sum+number # decrement the number number = number-1 # print the sum print("Sum of natural numbers", "=", sum)

**Output:**

Sum of natural numbers = 15

### Method #3:Using mathematical formula

Instead of iterating till number the best and efficient solution is to use mathematical formula given below.

**Formula:**

sum = ( n * (n +1) ) / 2

**Below is the implementation:**

# given number number = 5 # Using mathematical formula sum = (number * (number+1))//2 # print the sum print("Sum of natural numbers till", number, "=", sum)

**Output:**

Sum of natural numbers till 5 = 15

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