What is the frequency of blue light that has a wavelength of 446 nm?
i need the answer in hz

When I went through with the math, the answer I came upon was: 
6.67 X 10^14 

Here is how I did it: First of all we need to know the equation. 

c=nu X lamda 
(speed of light) = (frequency)(wavelength) 
(3.0 X 10^8 m/s) = (frequency)(450nm) 

We want the answer in meters so we need to convert 450nm to meters. 
450nm= 4.5 X 10^ -7 m 
(3.0 X 10^8 m/s) = (frequency)(4.5 X 10^ -7 m) 

Divide the speed of light by the wavelength. 
(3.0 X 10^8m/s) / (4.5 X 10^ -7m) =6.67 X 10^ 14 per second or s- 

6.67 X 10^14 s- hope this helps

From Electromagnetic Waves,
Velocity  C = f *λ

Where C = Velocity in m/s. = 3 * 10^8 m/s.
            f = Frequency in Hertz     ( /s)
           λ = Wavelength in metres.

Wavelength of blue light = 446 nm = 446 nano metres = 446 * 10^-9 m.

f =  C / λ  = ( 3 *10^8) / (446 * 10^-9)    use your calculator.
               =  6.7265 * 10 ^ 14  Hertz.