AdventOfFogle.py

from random import uniform, seed
from math import sqrt
from multiprocessing import Pool, freeze_support

def f(count):
    seed()

    CIRCLES = ((10,10),(-10,10),(-10,-10), (10,-10))
    tot_count, in_count = 0, 0

    for _ in range(count):
        x,y = uniform(-10,10), uniform(-10,10)
            
        tot_count += 1
        in_count += all([sqrt((xx-x)**2+(yy-y)**2) <= 20.0 for xx,yy in CIRCLES])

    return (in_count, tot_count)

if __name__ == "__main__":
    freeze_support()
    
    POOL_SIZE, BATCH_SIZE = 23, 50000000

    p = Pool(POOL_SIZE)
    results = p.map(f, [BATCH_SIZE]*POOL_SIZE)

    in_count, tot_count = sum([x[0] for x in results]), sum(x[1] for x in results)
    print("in: ", in_count)
    print("tot:", tot_count)
    ratio = float(in_count)/tot_count
    print("ratio:", ratio)
    print("area: ", ratio * 400)

Added a seed() call to each process and it gets a lot better results