Need help counting time spent in presentation

[af11k]

I have a presentation that will be used by an operator to assemble a piece of equipment.
I need to account for the time used in the assembly process.
Timer will start when clicking the Start button on first slide. Timer will stop when clicking "Assembly Completed" on last slide.
Time will not be visible to the operator. Time will be sent to report in MS Word.

So far I think I can use DateDiff to get time difference from start to finish.

Can anybody help??

Thanks.

[SamT]

Will this assembly be completed in one session of PP?

DateDiff will work but so will

Dim StartTime as Double
Dim EndTime As Double
Dim Duration As String 

'OnStart: StartTime = CDbl(Now)
'OnCompletion: EndTime = CDbl(Now)

Duration = Format(EndTime - StartTime, "[h]:mm")

Microsoft stores DateTimes as decimal numbers, counting days from 1/1/1900 (usually.) Times are stored as decimal fractions of one day (1/(24x60x60x10ⁿ)). I don't know the value of ⁿ, but it works out to about 11 decimal places of Time.

Do you have to account for work breaks?