 So it says, what is the shortest wavelength line in nanometers in the Paskin series, which is N2 equals 3 and N1 equals infinity for hydrogen. So what do we need to do? We need to remember the Riefer equation. We also remember. So it gives us the values for our N1 is infinity and N2 is 3. So let's just plug this stuff in here. So I'll show you how I like to plug it in. N2, so again this is what we were talking about before we turned the camera on, this is infinity. Of course we know that doesn't really make sense to say 1 over infinity squared, but if we think about our calculus or whatever, this limit goes to 0. If you have a question, I'll call it an instructor. So let's go ahead and simplify. So 1.097 times 10 to the 7 divided by 1 meter times 1 minus 0. These problems will just make it standard to go to 3 significantly. It's okay because it doesn't really give us, these aren't figures to energy levels, aren't they? In fact they give you an infinite number of significant figures if you think about it that way. So 1, 2, 3, 4, 5, 6, but that's per meter, right? And that is also 1 over wavelength, right? So that's not what we want, we want wavelength. So all we do is flip this thing over, okay? So how do we do that? We say 1 meter divided by 1.22 times 10 to the 6, so 1, 3.20 times 10 to the negative 7 meters, like that. But it says it wants it in nanometers, so can I erase this part of the board? Is that all right? Is it okay with that? I mean, do you guys have it down yet? So do you guys remember how many nanometers are in a meter? And for the 9, right? And so I won't do this in my calculator and get it wrong. Okay, so did that make sense? Okay, so this one was a little harder because of that limit going to infinity. Are there any questions on this one? Again, it's mostly memorized, the equation memorized the constant.