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# Sum of series programs/examples in C programming language

**Sum of Series Programs in C** - This section contains programs to solve (get sum) of different mathematic series using C programming.

**Solved series are:**

**1+2+3+4+..N<**
**1^2+2^2+3^2+4^2+..N^2**
**1/1! + 2/2! + 3/3! + 4/4! + ... N/N!**
**1+ 1/2 + 1/3 + 1/4 + 1/5 + .. 1/N**
**1 + 3^2/3^3 + 5^2/5^3 + 7^2/7^3 + ... till N terms**

## Sum of Series Programs / Examples using C

#### 1) C program to find sum of all natural numbers.

**Series: 1+2+3+4+..N**

/*This program will print the sum of all natural numbers from 1 to N.*/
#include<stdio.h>
int main()
{
int i,N,sum;
/*read value of N*/
printf("Enter the value of N: ");
scanf("%d",&N);
/*set sum by 0*/
sum=0;
/*calculate sum of the series*/
for(i=1;i<=N;i++)
sum= sum+ i;
/*print the sum*/
printf("Sum of the series is: %d\n",sum);
return 0;
}

Enter the value of N: 100
Sum of the series is: 5050

#### 2) C program to find sum of the square of all natural numbers from 1 to N.

**Series: 1^2+2^2+3^2+4^2+..N^2**

/*This program will print the sum of the square of all natural numbers from 1 to N.*/
#include<stdio.h>
int main()
{
int i,N;
unsigned long sum;
/*read value of N*/
printf("Enter the value of N: ");
scanf("%d",&N);
/*set sum by 0*/
sum=0;
/*calculate sum of the series*/
for(i=1;i<=N;i++)
sum= sum+ (i*i);
/*print the sum*/
printf("Sum of the series is: %ld\n",sum);
return 0;
}

Enter the value of N: 100
Sum of the series is: 338350

#### 3) C program to find the sum of Natural Number/Factorial of Number of all natural numbers from 1 to N.

**Series: 1/1! + 2/2! + 3/3! + 4/4! + ... N/N!**

/*
This program will find the sum of Natural
Number/Factorial of Number of all natural numbers from 1 to N.
*/
#include<stdio.h>
/*function to find factorial of the number*/
unsigned long factorial(int num)
{
int i;
/*always assign 1, if variable multiplies with values*/
unsigned long fact=1;
/*multiply num*num-1*num-2*..1*/
for(i=num; i>=1; i--)
fact= fact*i;
/*return factorial*/
return fact;
}
int main()
{
int i,N;
float sum;
/*read value of N*/
printf("Enter the value of N: ");
scanf("%d",&N);
/*set sum by 0*/
sum=0.0f;
/*calculate sum of the series*/
for(i=1;i<=N;i++)
sum = sum + ( (float)(i) / (float)(factorial(i)) );
/*print the sum*/
printf("Sum of the series is: %f\n",sum);
return 0;
}

Enter the value of N: 10
Sum of the series is: 2.718282

#### 4) C program to find sum of following series:

**1+ 1/2 + 1/3 + 1/4 + 1/5 + .. 1/N**

/*
C program to find sum of following series
1+ 1/2 + 1/3 + 1/4 + 1/5 + .. 1/N
*/
#include<stdio.h>
int main()
{
int i,N;
float sum;
/*read value of N*/
printf("Enter the value of N: ");
scanf("%d",&N);
/*set sum by 0*/
sum=0.0f;
/*calculate sum of the series*/
for(i=1;i<=N;i++)
sum = sum + ((float)1/(float)i);
/*print the sum*/
printf("Sum of the series is: %f\n",sum);
return 0;
}

Enter the value of N: 10
Sum of the series is: 5.187378

#### 5) C program to find sum of following series:

**1 + 3^2/3^3 + 5^2/5^3 + 7^2/7^3 + ... till N terms**

/*
C program to find sum of following series
1 + 3^2/3^3 + 5^2/5^3 + 7^2/7^3 + ... till N terms
*/
#include<stdio.h>
#include<math.h>
int main()
{
int i,N;
float sum;
int count;
/*read value of N*/
printf("Enter total number of terms: ");
scanf("%d",&N);
/*set sum by 0*/
sum=0.0f;
/*calculate sum of the series*/
count=1;
for(i=1;i<=N;i++)
{
sum = sum + ( (float)(pow(count,2)) / (float)(pow(count,3)) );
count+=2;
}
/*print the sum*/
printf("Sum of the series is: %f\n",sum);
return 0;
}

Enter total number of terms: 10
Sum of the series is: 2.133256