(300/100) = 3 metres.

Speed of light and radio frequency are in millions of metres/ Hertz per second, so you can dispense with lots of 0's.

λ = V/f = 3*10^8 m/sec/(1*10^8) sec^-1 = 3.00 m

λ=c/f = (3 x 10⁸ m/s)/(100 x 10⁶ Hz) = 3m

That is not the speed of light, it should be 3x10^8 m/s

wavelength = speed/frequency = 3e8/1e8 = 3 meters