C program to find sum of first n natural numbers
This C program is to find the sum of first n natural numbers. Natural numbers are non-negative integers.
For eg if we take summation of 3 natural numbers 1,2,3 then their sum=6
Logic
Take a for loop starting with 0 keep incrementing the value of i and add it to the previous value.
Dry Run of the Program
Take input ‘n’ .Let us take n=3 //So it will give summation of 4 natural numbers
1st iteration for(i=0;i<=n;i++) i.e. for(i=0;i<=3;i++)
sum=sum+i i.e sum = 0 + 0 hence sum=0
2nd iteration for(i=1;i<=n;i++) i.e. for(i=1;i<=3;i++)
sum=sum+i i.e sum = 0 + 1 hence sum=1
3rd iteration for(i=2;i<=n;i++) i.e. for(i=2;i<=3;i++)
sum=sum+i i.e sum = 1 + 2 hence sum=3
4th iteration for(i=3;i<=n;i++) i.e. for(i=3;i<=3;i++)
sum=sum+i i.e sum = 3 + 3 hence sum=6
So output we get as sum = 6 for n=3.
Program
#include<stdio.h> void main() { int i,n,sum=0; printf("Enter how many terms you want to add\n"); scanf("%d",&n); for(i=0;i<=n;i++) { sum=sum+i; } printf("Summation of first %d natural numbers = %d\n",n,sum); }