You want to convert nm to m.
1.00 x 10^-3 nm=1.00 x 10^-12 m
Use both equations: E=hν and c=λν
Use the second equation to find the frequency so you can plug it into the energy equation.
c=λν
(3.00 x 10^8 m/s)=(1.00 x 10^-12 m)ν
Rearrange to solve for ν:
(3.00 x 10^8 m/s)/(1.00 x 10^-12 m)=ν
3.00 x 10^-20 Hz=ν
Use 1st equation to find the energy:
E=hν
E=(6.626 x 10^-34 J*s)(3.00 x 10^-20 Hz)
E=1.99 x 10-13 J