The Milky Way Galaxy, which is the galaxy in which our Solar System resides, is estimated to contain anywhere between 100 billion to 400 billion stars. The exact number is uncertain due to the challenges of accurately counting and studying stars across vast distances.
As for the total number of stars in all galaxies, it's challenging to provide an exact figure since the observable universe contains billions of galaxies, each with varying sizes and star populations. However, astronomers estimate that there are approximately 100 billion to 200 billion galaxies in the observable universe.
To give you a rough estimate, if we take a conservative estimate of 100 billion galaxies, and if each galaxy has, on average, 100 billion stars, then the total number of stars in all galaxies would be approximately 10 sextillion (10^22) stars. However, it's important to note that this is a very rough estimate, and the actual number could be significantly different.
It's worth mentioning that these estimates are based on our current understanding and observations of the universe, but our knowledge is continually evolving as new observations and discoveries are made.