You can't fit Earths *inside* the sun, but you can fit a lot of them *within its volume*. Here's the breakdown:

* Sun's volume: Approximately 1.41 x 10¹⁸ km³

* Earth's volume: Approximately 1.08 x 10¹² km³

Dividing the sun's volume by Earth's volume gives us:

1.41 x 10¹⁸ km³ / 1.08 x 10¹² km³ ≈ 1.3 x 10⁶

Therefore, you could fit approximately 1.3 million Earths inside the volume of the sun.