What Wavelength Does a 100mW Laser Deliver 3.5x10^17 Photons in One Second?

[Jethom18]

Homework Statement

At what wavelength does a 100mW laser deliver 3.5 x 10¹⁷ photons in one second?
h (plancks) = 6.626x 10^^-34
c = 3 x 10^⁸

Homework Equations

E = hf ==> E = hc / n (wavelength) ==> n = hc / E
Power = Energy / Time

The Attempt at a Solution

Energy = Power * Time ==> (100x10^-3 W)(3.5x10^17 photons)(1 second) = 3.5x10^16
n = hc / E ==> (3x10^8)(6.626x10^-34) / (3.5x10^16) = 5.65 x 10 ^-42 m

I think I calculated energy incorrectly, but I don't know any other formula I could use. Any help is appreciated..

Thanks!

 

[rock.freak667]

So 1 photon has an energy of (hc/λ )

3.5 x 10¹⁷ photons will have how much energy?