1. Find the volumes:

* Pluto's volume: Approximately 6.96 x 10^9 cubic kilometers

* Mars' volume: Approximately 1.63 x 10^11 cubic kilometers

2. Divide Mars' volume by Pluto's volume:

(1.63 x 10^11 cubic kilometers) / (6.96 x 10^9 cubic kilometers) ≈ 23.4

Therefore, you could fit approximately 23.4 Plutos inside Mars.

Important Note: This is a simplified calculation. It assumes both bodies are perfect spheres and that there's no wasted space when fitting Plutos into Mars. In reality, the shape of the bodies and the packing arrangement would make it difficult to perfectly fill Mars with Plutos.