# Sum of all odd natural numbers in range L and R

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 = 5Output:8 3 + 5 = 8Input:L = 7, R = 13Output: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 <bits/stdc++.h>` `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

`<?php` `//PHP program to print the sum` `// of all numbers in range L and R` `// Function to return the sum of` `// all odd natural numbers` `function` `sumOdd(` `$n` `)` `{` ` ` `$terms` `= (int)(` `$n` `+ 1) / 2;` ` ` `$sum` `= ` `$terms` `* ` `$terms` `;` ` ` `return` `$sum` `;` `}` `// Function to return the sum` `// of all odd numbers in range L and R` `function` `suminRange(` `$l` `, ` `$r` `)` `{` ` ` `return` `sumOdd(` `$r` `) - sumOdd(` `$l` `- 1);` `}` `// Driver Code` ` ` `$l` `= 2;` ` ` `$r` `= 5;` ` ` `echo` `"Sum of odd natural numbers from L to R is "` `,` ` ` `suminRange(` `$l` `, ` `$r` `);` `?>` |

## Javascript

`<script>` `//JavaScript program to print the sum` `// of all numbers in range L and R` `// Function to return the sum of` `// all odd natural numbers` `function` `sumOdd(n)` `{` ` ` `terms = (n + 1) / 2;` ` ` `sum = terms * terms;` ` ` `return` `sum;` `}` `// Function to return the sum` `// of all odd numbers in range L and R` `function` `suminRange(l, r)` `{` ` ` `return` `sumOdd(r) - sumOdd(l - 1);` `}` `// Driver Code` `let l = 2;` `let r = 5;` ` ` `document.write(` `"Sum of odd natural numbers from L to R is "` `+` ` ` `suminRange(l, r));` ` ` `// This code is contributed by sravan kumar` `</script>` |

**Output:**

Sum of odd natural numbers from L to R is 8