Some gamma rays originating in deep space have wavelengths on the order of 1 times 10 to the -18m, whereas an average radio wave has a wavelength on the order of 500m. The energy associated with each of these radiations is as follows: gamma ray = 2 times 10 to the -7 J; radio wave = 4 times 10 to the -28 J. By which factor are these gamma rays more energetic than an average radio wave?

Simple division here.