I used fair amount of excel that is the reason why I am commenting. Just because you can enter some numbers in cell you cannot call it a spreadsheet. The main problem I see in your spreadsheet is the data entry. After you enter something you have to hit tab. no other key works. The main feature for any spreadsheet should be ease of data entry. Also other feature should be selecting the cell with mouse (instead of entering A1 I should be able to select A1)