how do I Calculate elapsed time worksheet is open

[Guest]

I want to be able to calculate the amount of time that I am working in a
worksheet and display the elapsed in a cell so I can use it in time tracking.
Can this be done?

 

[Guest]

When you open a worksheet... type in 1 cell

=Now()

Copy that and Paste Special Values in to that cell

Then in another cell type

=NOW()-"The other cell"

Then change the format for that cell to Time, and change it to the 13:00

So everytime you want to update it, press F9. Im sure you can have some
worksheet event that does it automatically but I don't know exactly how to do
that.