Using drand48:
      10  2.73861279
     100  3.06186218
    1000  3.15964572
   10000  3.14632429
  100000  3.13988122
 1000000  3.14035598
10000000  3.14143144
       Pi 3.14159265358979

Using ChaCha20:
      10  3.16227766
     100  3.18896402
    1000  3.17287158
   10000  3.15675816
  100000  3.14329189
 1000000  3.13978836
10000000  3.14138726
       Pi 3.14159265358979

Using /dev/urandom:
      10  3.46410162
     100  3.03821810
    1000  3.11588476
   10000  3.14217962
  100000  3.13643021
 1000000  3.14020372
10000000  3.14130744
       Pi 3.14159265358979