Python can be used for doing Mathematical Stuff specifically using **Math Module**, in this article I fill discuss **How to find some of first n Natural Numbers using Python?** Natural Numbers sequence start from 1 and goes up to positive infinity. So first **5 Natural Numbers will be 1, 2, 3, 4, 5** and **first 10 Natural Numbers will be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10**.

Let’s for fininding sum of first 5 Natural Numbers, you need to do 1 + 2 + 3 + 4 + 5 but mathematically this summation can be sequezed in as n(n+1)/2 where n is number of **Natural Numbers**. Like for finding sum of first 5 natural numbers instead of doing 1 + 2 + 3 + 4 + 5, just do 5(5+1)/2 = 5(6)/2 = 15.

Quite Simple, so there can be two approaches for finding Sum of N Natural Numbers, let’s implement both of these and write **Python Code for finding sum of n Natural Numbers**.

Table of Contents

## 1) Python Code for Finding Sum of N Natural Numbers

```
# Sum of natural numbers up to n num
n = 10
# Checks if number is negative
if n < 0:
print("Enter a positive number")
else:
sum = 0
# use while loop to iterate until zero
while(n > 0):
sum += n
n -= 1
print("The sum is => ", sum)
```

**Output**

`The sum is => 55`

Similarly, if you want to ask your user about **How many Natural Numbers sum to find?** then instead of having n = 10 on **line 2** with **n = input(‘Enter A Number’)**.

## 2) Short Way for Finding Sum of N Natural Numbers Using Python

```
# Sum of natural numbers up to n num
user_input = input("Enter a Number => ")
# Converting to int as input() by default is a string
n = int(user_input)
# Checks if number is negative
if n < 0:
print("Enter a positive number")
else:
sum = n * (n + 1)/2
print("The sum is => ", sum)
```

When running the above code, a prompt will be shown to user **Enter a Number =>** after user enters number then code will be executed. If user entered non-negative then above code will show “**Enter a positive number**” otherwise code will execute and return **sum of N Natural Numbers**.

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