Trying to Divide a duration by number

Hello, 
I am working on doing time studies in a manufacturing environment.  I have Start/Stop time of operations into a "duration" field.  During this "duration", that may have yielded 10 widgets.  I am trying to divide that duration by the 10 widgets to calculate a duration per widget.  I am having trouble with QB letting me divide a duration by a number.

Thanks for your help

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Sam Ulmer
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