Finding wave number range for 1ns pulses of laser and radio waves

[Winzer]

Homework Statement

A 1ns pulse of electromagnetic waves would be 30cm long.
a) Consider such a pulse of 633 nm wavelength laser light. Find its central wavenumber and the range of wave numbers it is comprised of.
b) Repeat a except for a 1ns pulse of 100MHz radio
waves.

Homework Equations

$$k=\frac{2\pi}{\lambda}$$

The Attempt at a Solution

I got the central wavenumber with the above equation. But I am at a lost on where to go from there.

 

[Winzer]

Do I have to deal with the gaussian wave packet & fouier transform?