2.99792458 x [tex]10^{8}[/tex] m/s
To do this, take the original number and move the decimal place so there is only one value before it (in our case getting 2.99892458).
For every place you move the decimal to the left, raise 10 to that power (we moved the decimal 8 places to the left, so it becomes 10 raised to positive 8).
If you had to move the decimal to the right, for every place you had to move the decimal, you would raise 10 to that negative power.