[MeanWestTexan]

It's hard to know how many stars there are in the Milky Way because (among other factors: (1) it's difficult to know how big any given star is (from much bigger to 1/10 the size of Sol); (2) we can't see much of the MW; (3) mass of the MW is somewhat of a guess as there appears to be "stuff" outside Sol's orbit, etc.

[RightWhale]

There are 100 billion stars in the Milky Way.

There are 100 billion neurons in the human brain.

There are 100 billion galaxies in the Hubble volume.

There are 100 billion Hubble volumes in the entire universe.

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Some may find this limiting.