What is the accepted speed of light in a vacuum, to three significant figures?

1. The speed of light in a vacuum is accepted as a basic physical quantity with the fixed value 2.99792458 x 10^8 m/s. 2. Rounded to three significant figures this is 3.00 x 10^8 m/s. 3. That rounded value is the one used whenever three-digit accuracy is enough. 4. The value 2.26 x 10^8 m/s is the figure Roemer's 1676 data gave, about 25 percent adrift of the modern number. _Source: OpenStax College Physics (CC BY 4.0), Ch 25 "Geometric Optics", section 25.3 The Law of Refraction_