Since Mach 1 is the speed of sound, we will have to divide the speed of light by the speed of sound to work out how many Mach's the speed of light is.
We have
[tex]\dfrac{\text{ speed of light}}{\text{ speed of sound}}=\dfrac{2.998\cdot10^8\text{ m/s}}{340.27\text{ m/s}} \approx 881040[/tex]
