# C++ Program for sum of arithmetic series

Given with ‘a’(first term), ‘d’(common difference) and ‘n’ (number of values in a string) and the task is to generate the series and thereby calculating their sum.

## What is an Arithmetic series

Arithmetic series is the sequence of numbers with common difference where the first term of a series is fixed which is ‘a’ and the common difference between them is ‘d’.

It is represented as −

a, a + d, a + 2d, a + 3d, . . .

## Example

Input-: a = 1.5, d = 0.5, n=10
Output-: sum of series A.P is : 37.5
Input : a = 2.5, d = 1.5, n = 20
Output : sum of series A.P is : 335

Approach used below is as follows

• Input the data as the first term(a), common difference(d) and the numbers of terms in a series(n)
• Traverse the loop till n and keep adding the first term to a temporary variable with the difference
• Print the resultant output

## Algorithm

Start
Step 1-> declare Function to find sum of series
float sum(float a, float d, int n)
set float sum = 0
Loop For int i=0 and i<n and i++
Set sum = sum + a
Set a = a + d
End
return sum
Step 2-> In main()
Set int n = 10
Set float a = 1.5, d = 0.5
Call sum(a, d, n)
Stop

## Example

Live Demo

#include<bits/stdc++.h>
using namespace std;
// Function to find sum of series.
float sum(float a, float d, int n) {
float sum = 0;
for (int i=0;i<n;i++) {
sum = sum + a;
a = a + d;
}
return sum;
}
int main() {
int n = 10;
float a = 1.5, d = 0.5;
cout<<"sum of series A.P is : "<<sum(a, d, n);
return 0;
}

## Output

sum of series A.P is : 37.5