# C Program to Calculate Value of PI using Leibniz Formula

The Leibniz formula is an infinite series method of calculating Pi. The formula is a very simple way of calculating Pi, however, it takes a large amount of iterations to produce a low precision value of Pi.

Leibniz formula:
π/4 = 1 - 1/3 + 1/5 - 1/7 + 1/9 - ...
Or, π = 4 ( 1 - 1/3 + 1/5 - 1/7 + 1/9 - ... )

In this program we first read number of term to consider in series from user and then apply Leibniz formula to caluclate value of Pi.

## C Source Code: Calculation of Pi using Leibniz Formula

``````
#include<stdio.h>
#include<conio.h>
#include<math.h>

int main()
{
long int i, n;
double sum=0.0, term, pi;

printf("Enter number of terms: ");
scanf("%ld", &n);

/* Applying Leibniz Formula */
for(i=0;i< n;i++)
{
term = pow(-1, i) / (2*i+1);
sum += term;
}
pi = 4 * sum;

printf("\nPI = %.6lf", pi);

return 0;
}
``````

## Output

```Enter number of terms: 1000000

PI = 3.141592
```
To get more accurate result use higher value of n.