Answer
$1,304,396\space or\space 1.3\times10^{6}$
Work Step by Step
Let's assume the sun & the earth as spheres, then we can write,
Volume of the sphere $= \frac{4}{3}\pi r^{3}$ ; r is the radius of the sphere.
Radius of the sun = $696\times10^{6}\space m$ ; From Appendix E
Radius of the earth = $6.39\times10^{6}\space m$ ; From Appendix E
The volume of the sun $= \frac{4}{3}\pi (696\times10^{6}\space m)^{3}\space -(1)$
The volume of the earth $= \frac{4}{3}\pi (6.39\times10^{6}\space m)^{3}\space -(2)$
From $(1)/(2)=\gt$
No. of earth fit inside the sun $=\frac{\frac{4}{3}\pi (696\times10^{6}\space m)^{3}}{ \frac{4}{3}\pi (6.39\times10^{6}\space m)^{3}}$
$\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space=\frac{696^{3}}{6.37^{3}}$
$\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space =1,304,396$
$\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space\space= 1.3\times10^{6}$
