Question

How far does light travel in 1 nano second?

Answer 1

speed of light is around one foot per nanosecond. One foot is about 12 inches. Light travels approximately 12 inches in one nanosecond.

Answer 2

Speed of light can be approximated to 3×10⁸ m/s. 
That is, light travels 3×10⁸ m in 1 seconds
Let it travels x meters in 1 nano seconds(10⁻⁹)
Therefore, 
3×10⁸=1
x = 10⁻⁹
x = 3×10⁸×10⁻⁹ = 0.3 meters.