I have a file with a sheet for each week (52 all in) which is a form that gets filled in weekly. One cell on sheet 2 ('Sheet2'!A10 for example) represents the value of the previous week ('Sheet1'!A10) and adds half of the value of 'Sheet1'!A8. So, the formula in 'Sheet2'!A10 = 'Sheet1'!A10 +...