How many solar systems are there in the universe? How many in the known universe?

Then they discuss some nebulous objects that may or may not count as stars. Every star has something orbiting it, mostly rocks and dust, so let's say about a quarter of them are in the "sweet spot" of being able to hold some of the current definition of "planet." According to Wikipedia, "The Milky Way contains between 200 and 400 billion stars and at least 100 billion planets."

The Milky Way is apparently average-sized, so each of those tiny dots we can only see with the Hubble also has something on the order of half a trillion stars, a quarter of which almost certainly have some planets. And that's just the Milky Way. There are billions, possibly trillions of galaxies. The Hubble space telescope likes to scope out previously uncharted empty areas of the sky and zero in, and it inevitably sees new galaxies every time it does this.

Assuming our solar system is typical, a low estimate for the extrapolated universe is 10 to the 24th power solar systems with planets, or 1,000,000,000,000,000,000,000,000, or a trillion trillion. Multiply this by eight or nine to get the total number of planets, and expect that number to increase as we inevitably discover the universe is bigger than we previously imagined.

The exact number of solar systems in the universe is not known, but estimates suggest there could be hundreds of billions to trillions. In the known universe, which encompasses the observable universe, there are estimated to be billions of galaxies, each potentially containing billions of solar systems.