1 * 10^78 atoms/universe
Work Step by Step
Take the density and the volume in ml of the sun ( 4/3pi r^3) using the radius given. Then using density= mass/ volume solve for mass and then convet to moles and then to atoms by using Avogadro's number 6.022x 10^23. Finally multiply this answer by 100 billion and then 10 billion. And that will give the answer.