Wavelength = (speed) / (frequency)
Wavelength = (300 thousand km per second) / (10.5 billion per second)
Wavelength = (300 / 10.5) (thousand km per second) / (billion per second)
Wavelength = (28.57) (million meters / second) / (thousand million / second)
Wavelength = (28.57) (meters / second) / (thousand / second)
Wavelength = (28.57) (meters / thousand)
<em>Wavelength = (28.57) (millimeters) </em>