# How to Calculate the Value of Pi in Python

In this example, we will learn how to calculate the value of pi (π) using a Monte Carlo method in Python.

### Source Code

``````#! /usr/bin/env python3
# -*- coding: utf-8 -*-
# computePi.py
# Calculate the value of pi by using Monte Carlo method in Python

import random
import math

def main():
n = int(input())            # n is the number of random points
total = 0                       # total is the number of random points inside the circle

for i in range(n):
x = random.random()
y = random.random()

if math.sqrt(x**2 + y**2) < 1.0:   # judge whether the point is inside the circle
total += 1

piResult = 4.0 * total / n                   # obtain the value of Pi

print('After ', n, ' loops, calculated value of Pi：', piResult)
print('Actual value of Pi：', math.pi)
print('The error：', abs(math.pi - piResult) / math.pi)

if __name__ == '__main__':
main()
``````

After running the codes above, we can get these results:

1) The number of iterations is set to 100.

2) The number of iterations is set to 1000.

3) The number of iterations is set to 10000.

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