# One estimate is that there are 1010 stars in the Milky Way galaxy, and that there are 1010 galaxies in the universe. Assuming that the number of stars in the Milky Way is the average number, how many stars are in the universe?

${10}^{20}$
I assume that your 1010 means ${10}^{10}$.
Then the number of stars is simply ${10}^{10} \cdot {10}^{10} = {10}^{20}$.