Average of even numbers till a given even number

• Last Updated : 16 Dec, 2021

Given an even number n, find the average of even numbers from 1 to n.
Examples :

Input : 10
Output : 6
Explanation:
(2 + 4 + 6 + 8 + 10 )/5
= 30/5
= 6

Input : 100
Output : 51

Method 1
We can calculate average by adding each even numbers till n and then dividing sum by count.

C++

 // Program to find average of even numbers// till a given even number.#include   // Function to calculate the average// of even numbersint averageEven(int n){    if (n % 2 != 0) {        printf("Invalid Input");        return -1;    }      int sum = 0, count = 0;    while (n >= 2) {          // count even numbers        count++;          // store the sum of even numbers        sum += n;          n = n - 2;    }    return sum / count;}  // driver functionint main(){    int n = 16;    printf("%d", averageEven(n));    return 0;}

Java

 // Program to find average of even numbers// till a given even number.import java.io.*;  class GFG {      // Function to calculate the average    // of even numbers    static int averageEven(int n)    {        if (n % 2 != 0) {        System.out.println("Invalid Input");            return -1;        }          int sum = 0, count = 0;        while (n >= 2) {           // count even numbers         count++;           // store the sum of even numbers         sum += n;           n = n - 2;        }        return sum / count;    }      // driver function    public static void main(String args[])    {        int n = 16;        System.out.println(averageEven(n));    }}  /*This code is contributed by Nikita Tiwari.*/

Python3

 # Program to find average of# even numbers till a given# even number. # Function to calculate the# average of even numbersdef averageEven(n) :     if (n % 2 != 0) :        print("Invalid Input")        return -1         sm = 0    count = 0     while (n >= 2) :         # count even numbers        count = count + 1         # store the sum of even        # numbers        sm = sm + n         n = n - 2         return sm // count # driver functionn = 16print(averageEven(n)) # This code is contributed by Nikita Tiwari.

C#

 // C# Program to find average// of even numbers till a// given even number.using System; class GFG {     // Function to calculate the    // average of even numbers    static int averageEven(int n)    {        if (n % 2 != 0) {        Console.Write("Invalid Input");            return -1;        }         int sum = 0, count = 0;        while (n >= 2) {         // count even numbers        count++;         // store the sum of even numbers        sum += n;         n = n - 2;        }        return sum / count;    }     // driver function    public static void Main()    {        int n = 16;        Console.Write(averageEven(n));    }} /*This code is contributed by vt_m.*/

PHP

 = 2)    {         // count even numbers        \$count++;         // store the sum of        // even numbers        \$sum += \$n;         \$n = \$n - 2;    }    return \$sum / \$count;}     // Driver Code    \$n = 16;    echo(averageEven(\$n));     //This code is contributed by vt_m.?>

Javascript



Output:

9

Method 2
The average of even numbers can be find out only in single steps
by using the following formula :-
[n + 2 ] / 2 where n is last even number.
How does this formula work?
We know there are (n)/2 even numbers till n. For example there are two even number till 4 and there are three even numbers till 6.
Sum of first k even numbers is k * (k + 1)
Putting k = n/2, we get sum of first n/2 even numbers as n/2(n/2 + 1)
Average of first n/2 even numbers (or even numbers till n) = (n + 2)/2

C++

 // Program to find average of even numbers// till a given even nend number.#include using namespace std;  // Function to calculate the average// of even numbersint averageEven(int n){    if (n % 2 != 0) {        cout<<"Invalid Input";        return -1;    }      return (n + 2) / 2;}  // driver functionint main(){    int n = 16;    cout<

C

 // Program to find average of even numbers// till a given even number.#include   // Function to calculate the average// of even numbersint averageEven(int n){    if (n % 2 != 0) {        printf("Invalid Input");        return -1;    }      return (n + 2) / 2;}  // driver functionint main(){    int n = 16;    printf("%d", averageEven(n));    return 0;}

Java

 // Program to find average of even numbers// till a given even number.import java.io.*; class GFG {         // Function to calculate the average    // of even numbers    static int averageEven(int n)    {        if (n % 2 != 0) {        System.out.println("Invalid Input");            return -1;        }         return (n + 2) / 2;    }     // driver function    public static void main(String args[])    {        int n = 16;        System.out.println(averageEven(n));    }} /*This code is contributed by Nikita Tiwari.*/

Python3

 # Python3 program to find average of even# numbers till a given even number. # Function to calculate the# average of even numbersdef averageEven(n) :    if (n % 2 != 0) :        print("Invalid Input")        return -1         return (n + 2) // 2     # Driver functionn = 16print(averageEven(n)) # This code is contributed by Nikita Tiwari.

C#

 // C# Program to find average// of even numbers till a// given even number.using System; class GFG {         // Function to calculate the    // average of even numbers    static int averageEven(int n)    {        if (n % 2 != 0) {        Console.Write("Invalid Input");            return -1;        }         return (n + 2) / 2;    }     // driver function    public static void Main()    {        int n = 16;        Console.Write(averageEven(n));    }} /*This code is contributed by vt_m.*/



Javascript



Output :

9

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