Program to Find the Average of First n Natural Numbers

Here is a program to find the average of first n natural numbers using for loop with output and explanation.

# include <stdio.h> 
# include <conio.h> 
void main() 
{ 
 int n, i ; 
 float sum = 0, avg ; 
 clrscr() ; 
 printf("Enter the limit : ") ; 
 scanf("%d", &n) ; 
 for(i = 1 ; i <= n ; i++) 
  sum = sum + i ; 
 avg = sum / n ; 
 printf("\nAverage of first %d numbers is : %.2f", n, avg) ; 
 getch() ; 
} 

Output of above program

Enter the limit : 5

Average of first 5 numbers is : 3.00

Explanation of above program

In this program to calculate average of first n natural numbers, we have two integers (n, i) and two floating point (sum, avg) variables. First we initialize the variable sum to zero and then ask user to enter a limit. Now inside the for loop which runs from 1 to n, we're calculating the sum first by simply adding the loop variable ( i )with our variable ( sum ) as we're working on first n numbers. Then outside the loop we are calculating the average by dividing the total sum by n and then we're displaying the average.

Remember: If you notice carefully, we haven't placed any curly brackets ( {} ) in our for loop as our for loop contains only one statement. And in C you can omit curly brackets from any loop including for, while, do-while as well as from conditional statements (if else), if and only if there is only one statement inside that particular block just like we have here in our for loop.