# Java Program to calculate Sum of 1 to N Numbers using Recursion

/* Sum of 1 to N natural numbers can be calculated using for / while loop very easily. In the below java program we have calculated sum of 1 to N numbers using recursive function without using any loop. In Recursive, the function calls itself until some condition is met. In our example, **sumR(int num)** is called until num becomes 1 .

The following code calculates Sum 1 to N numbers */

package com.javaonline; import java.io.*; // This program computes sum 1 to N numbers using recursion public class SumRecursion { public static void main(String[] args) { System.out.println("Enter N"); try { BufferedReader br = new BufferedReader( new InputStreamReader(System.in)); int number= Integer.parseInt(br.readLine()); // reads number as a string from keyboard and converts to number /* Scanner sc = new Scanner(System.in); // We can also use this lines for getting N int number = sc.nextInt(); */ int sum = sumR(number); // calling sumR function System.out.println("Sum of " + number + " Numbers using Recursion is : " + sum); } catch (Exception e) { System.out.println ("Give Proper Input i.e. Enter Numeric value only and with in range"); } } // Computes a Sum of N numbers by recursion. public static int sumR(int num) { int sum; if(num==1) return(1) ; else sum=num + sumR(num-1); // function calls itself return sum; } }

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