Answer: 9 × 10¹⁶ m²/s² (square of speed of light in vacuum)
Explanation:
Einsteins' energy mass relation:
E = mc²
Where, E is energy, m is mass and c is the speed of light.
The ratio of rest energy to rest mass:

speed of light in vacuum is 3 × 10⁸ m/s
Hence, the numerical quantity of the ratio of rest energy/ rest mass = (3 × 10⁸ m/s)² = 9 × 10¹⁶ m²/s².