I need to edit my budget, and the first one I'm going to put through is the number of teaching assistants there'll be two. So it's very tempting to be naughty here and go down to the teaching assistant cost in course one and just multiply it by a two.

Oh, all that makes me feel bad. Horribly bad practice there. I've now hardcoded into a formula, very naughty, but I've now got inconsistent formulas and on on my row and inconsistent formulas in the column. Ooh, we definitely want to avoid this. Instead, we want to insert an assumption. So let me get rid of that and let's have a think about what we'll do. The assumption here is nothing to do with costs, so I won't put it in my cost section. Instead, I'll put it in the other assumption section.

I need to insert some rows here, so I'm going to click on row 37 with my mouse. Then right click it and insert a row. I'm actually going to insert a second one while I'm here.

Now the formatting has copied down from the cells above. That's fantastic. If it hasn't for you, then you can of course go up to the home ribbon and you could use format painter and then copy that into the cells below. So what do I want to do here? I definitely need to include the number of teaching assistants. So let's do that in this second line here. Number of teaching assistants, and we know for course one that there'll be a two, but I don't want to just link to that two. If I just linked that two again, I'll have an inconsistent formula for course two. Instead, I'd love to put a one in there.

Now, I could update my teaching assistant cost linking up to the course one, and course two could have a consistent formula. It would link up to that assumption as well. But I want to go one step further. If the number of teaching assistants might change, then the number of course leaders might change. So let's put an assumption in for that.

I'm now making my model flexible for the future. I'm still gonna keep them as one-on-one, but what I can now do is I can update just this course leader cost here, and then I can drag it to the right and down.

Let's do it. Let's update that formula. I'll multiply that by the number of course leaders one, and I don't need to put any dollar signs in. I want this to move to the right, and I want it to move down, so I press enter, drag it to the right and watch the numbers. They don't change, but watch what happens when I drag this down, the teaching assistant cost in course one did update fantastic, and I've still got consistent formulas as I go across the rows, and I've got consistent formulas in the column as well. Great.