I saw another question which says the speed of light is "$3\times 10^8 \:\rm m/s$", and I know that the speed of light is $299,792,458\ \rm m/s$.

My chemistry teacher taught me that $3.0$ means $3.0 \pm 0.05$, so it is a range from $2.95$ to $3.05$. My chemistry teacher also taught me that $3$ means "exactly $3$ without any range".

How does this work with a number like $3\times 10^8$?

Does the lack of a decimal point mean that the number is exactly $300,000,000$ with no range?

Is it accurate to say that the speed of light is $3\times 10^8\:\rm m/s$?

*My question is about precision, not about the speed of light.*