The first thing we check is that the balance sheet balances, I go down to my balance check and it is zero in every period I now want to go looking for any other unusual items You may want to have a look in the balance sheet calculations section You may want to pause now and have a look on your own and then come back for the debrief So I go up to my balance sheet calculations, and what do we notice? Well as I go through these items, I can see that D&A (depreciation and amortization) seems to be a level figure, 424.2 So that's the first thing that might suggest to me that something could be wrong Also, I know because I built the model that the assumption used here is a percentage of beginning long-term assets If we have a look at beginning long-term assets, beginning long-term assets is changing If I'm taking an assumption on a figure that's changing, I should have a D&A that is changing So they were the first symptoms! Next up, I'm going to reveal formulas by hitting ALT M H or alternatively you could of hit CTRL and then the acute accent button Which is on many keyboards, next to the number one key As I now scroll to the right, I'm looking for any unusual figures and I can see that in the D&A, there are some dollar signs That is locking onto a cell Now that's very unusual in this model, there are barely any dollar signs at all (any locks being used). That is a bad lock! We have locked onto F38 here and as I go to the right, again I'm in column G but I'm still linking to F38 I now go to column H, still linking to F38 So we shouldn't be locking that, let's turn that off again, ALT M H I go into my cell, press F2, so my cursor is now somewhere within that F38 And I can either delete the dollar signs or I could press F4 once, twice and then three times That's looking a bit better, I copy that to the right Yes! Depreciation is now changing, it looks a little bit more sensible