Hey, are the Excel formulae different on Mac? When I highlight the cells I want to sum up and press the "sum" symbol, it says there is an error. Also, the multiplication formula e.g. =(D1*G1) doesn't work. An error again. Sorry, I'm very new to this. Is there a list of formulae available? Honestly, I didn't understand what the programme was telling me, except for the "error" thing.