I've created a macro that changes the auto calc function to
manual(Tools|Options|Calculation|Manual). Here is the code it generates:

Sub AutoCalcOff()
' AutoCalcOff Macro
With Application
.Calculation = xlManual
.MaxChange = 0.001
End With
ActiveWorkbook.PrecisionAsDisplayed = False
End Sub

I'd like this macro to run automatically on opening this document - not sure
how to do this.

On close, I'd also like the system to be able to revert back to the previous
setting, i.e. if the auto-calc was previously set to automatic and the macro
changed it to manual, I'd like the setting to be returned to its previous
state.

Any ideas?

Thanks in advance.