In Excel the data are contained in ‘cells’ that are referenced using a grid numbering system similar to that used on maps.

You select a cell by clicking on it. Cell ‘D5’ is selected in the illustration below. It contains the value ‘8’. The formula bar shows the formula that led to that value, it is the addition of the contents of cells ‘C3’ and ‘D3’:

5 + 3 = 8

If you change the values in any of the source cells ('C3' or 'D3') then the value in 'D5' will automatically update:

The power of Excel lies in this. You set up the 'model'. If you subsequently change any 'input' data values then all the formulae that use those values are automatically updated. There can be as many links as you wish in the 'chain' of formulae.

What value will be in cell 'D8'?   Roll your mouse over the image to check the answer.