 Okay, so let's try this problem, and let's just do it from the perspective of looking at the periodic table, okay? So if you've talked about transition elements or things past the D block, then that's cool, you should know about the N plus L rule, but if not, that's okay, but you can still do these problems. Let's just do it from looking at the periodic table and remember kind of the strange thing that happens when you get to the transition elements. But anyways, so the first one here is iron, this is another good one to memorize if you don't know. The second one is gallium, but it's actually in the 4P, so it's N equals P, but we'll talk about that in a second. Anyways, so let's just draw the full electron configuration of iron. So again, look at the periodic table, 1S2, 2S2, 6, 3S2, 6, 4S2, so those are all the ones that we've done so far, right, all the way up to calcium, 20 electrons, but now we get into the transition elements where you actually go back to N equals 3, so you go 3D, so of course that's the D block, but anyways then you just count to where iron is, 1, 2, 3, 4, 5, 6. So what you've got to remember is this kind of weird rule of the fill-in properties, electrons, that actually the 4S electrons are lower in energy. If you don't know, these are one lower than the S before it. So in that case, in that case let's do gallium and show kind of a similar principle, right? So here it's the same, so 1S2, 2S after the 4S, so they can hold 10 electrons, and then the 4, N equals 400, you can see how that direction you just do.