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Sum of all odd natural numbers in range L and R
• Last Updated : 05 Apr, 2021

Given two integers L and R, the task is to find the sum of all odd natural numbers in range L and R inclusive.
Examples:

```Input: L = 2, R = 5
Output: 8
3 + 5 = 8

Input: L = 7, R = 13
Output: 40```

A naive approach is to traverse from L to R and summate the elements to get the answer.
An efficient approach is to use the formula for calculating the sum of all odd natural numbers upto R and L-1 and then subtract sum(R)-sum(L-1).
Below is the implementation of the above approach:

## C++

 `// C++ program to print the sum``// of all numbers in range L and R``#include ``using` `namespace` `std;` `// Function to return the sum of``// all odd natural numbers``int` `sumOdd(``int` `n)``{``    ``int` `terms = (n + 1) / 2;``    ``int` `sum = terms * terms;``    ``return` `sum;``}` `// Function to return the sum``// of all odd numbers in range L and R``int` `suminRange(``int` `l, ``int` `r)``{``    ``return` `sumOdd(r) - sumOdd(l - 1);``}` `// Driver Code``int` `main()``{``    ``int` `l = 2, r = 5;``    ``cout << ``"Sum of odd natural numbers from L to R is "``         ``<< suminRange(l, r);` `    ``return` `0;``}`

## Java

 `// Java program to print the sum``// of all numbers in range L and R` `import` `java.io.*;` `class` `GFG {``   `   `// Function to return the sum of``// all odd natural numbers``static` `int` `sumOdd(``int` `n)``{``    ``int` `terms = (n + ``1``) / ``2``;``    ``int` `sum = terms * terms;``    ``return` `sum;``}` `// Function to return the sum``// of all odd numbers in range L and R``static` `int` `suminRange(``int` `l, ``int` `r)``{``    ``return` `sumOdd(r) - sumOdd(l - ``1``);``}` `// Driver Code``public` `static` `void` `main (String[] args) {``            ``int` `l = ``2``, r = ``5``;``    ``System.out.print( ``"Sum of odd natural numbers from L to R is "``        ``+ suminRange(l, r));``    ``}``}``// This code is contributed by shs..`

## Python3

 `# Python 3 program to print the sum``# of all numbers in range L and R` `# Function to return the sum of``# all odd natural numbers``def` `sumOdd(n):``    ``terms ``=` `(n ``+` `1``)``/``/``2``    ``sum1 ``=` `terms ``*` `terms``    ``return` `sum1` `# Function to return the sum``# of all odd numbers in range L and R``def` `suminRange(l, r):``    ``return` `sumOdd(r) ``-` `sumOdd(l ``-` `1``)``    ` `# Driver code``l ``=` `2``; r ``=` `5``print``(``"Sum of odd natural number"``,``      ``"from L to R is"``, suminRange(l, r))` `# This code is contributed by Shrikant13`

## C#

 `// C# program to print the sum``// of all numbers in range L and R``using` `System;` `class` `GFG``{``    ` `// Function to return the sum of``// all odd natural numbers``static` `int` `sumOdd(``int` `n)``{``    ``int` `terms = (n + 1) / 2;``    ``int` `sum = terms * terms;``    ``return` `sum;``}` `// Function to return the sum``// of all odd numbers in range L and R``static` `int` `suminRange(``int` `l, ``int` `r)``{``    ``return` `sumOdd(r) - sumOdd(l - 1);``}` `// Driver Code``public` `static` `void` `Main ()``{``    ``int` `l = 2, r = 5;``    ``Console.WriteLine( ``"Sum of odd natural numbers "` `+``                ``"from L to R is "` `+ suminRange(l, r));``}``}` `// This code is contributed by shs..`

## PHP

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## Javascript

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Output:
`Sum of odd natural numbers from L to R is 8`

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