First code:

**Calculate the value of Pi,

we can use the graph of a circle and find the area under the graph.

Riemann sum is an effective method for finding the area under the graph

Second code:

** 1-Write a PThreads Program that will calculate Pi

2-It should run 8 threads

3-Creat a global variable for the total sum

4-Use a Mutex variable to lock the critical section where you sum the results

5-The program should output the sum at each thread and the parent will output the total sum

6-Copy this version and remove the Mutex variable

7-run both versions and compare the output