We start our error checking by looking at the balance sheet, to see if it balances I go down to the balance check and it does. It balances in every single period But there still could be errors in my model I now want to go looking to see if there are any strange figures, maybe where figures change quite dramatically over the years If you do want a tip, have a look in the income statement You may want to pause the recording now and have a go on your own Okay, so up to the income statements and what do we notice? Well I can notice, if I look at some of the subtotals that they suddenly jump in number So earnings before continuing operations start at 13,000, go up to 13, 16 but then jump up to 29 I see something similar with earnings before tax, 17,000, 19,000, 35,000? That's quite a jump EBITDA has a similar jump, EBIT has a similar jump but gross profit seems okay, 40,000, 46,000, 52,000 So I think the issue occurs somewhere between gross profit and between EBIT So let's have a look at what's going on here, well EBIT in 2014, looks like it's been correctly calculated 2015, yep looks like it's been correctly calculated. 2016's our issue year, what happens here? We haven't included R&D expenses, oops! So again I need to correct that by adding in F30 That looks much tidier now, 16,000, 19,000, 21,000. Copy it to the right I now go down and check that the other sub totals look like they're behaving in a sensible way EBITDA looks much more sensible now Earnings before tax also looks more sensible. I have found my error