If you are ever stuck looking at a number and thinking "how is this calculated?!" try clicking the tile that the number is on. For example, click the Numbers tab at the top and select Current. Ensure the date is correct (red button on the right).
The underlying data is behind each of the tiles for the 7 key numbers. For further information and details about these figures, click the drop down in the top left hand side, select BusinessU and read the article entitled "Behind the 7 key numbers".