Timesheet calculation and drop down question

[sunshine1325]

In cells B7 and C7 I want to add the start time and finish time in maybe a drop down list of times in 30 min increments then the result is placed into B/C8 cell.

So for example Simona start at 8am and finishes at 10am - so in B/C8 it should total 2 hours

Can anyone help me with how to do the drop down and calculate the hours as this would be a drop down if this was used.

Thanks in advance

[torachan]

Please, please, please
Do not use merged cells.
torachan.

[AliGW]

If you are going to make a plea like this, please also explain to the OP why you are making it. It is highly likely that they don't know the problems that can be caused my merged cells.

[KOKOSEK]

I've create time hours in col T (does no matter where) with 30 min interval.
Then for cells B:O applied data validation as list (T1:T15).
into total cell (respectively) put (into B8)

=C7-B7

Check attached file.

[torachan]

@Ali, frustration showed very early today, most of us from bitter experience have learnt the hard way to avoid merged cells, they are pretty (pretty frustrating).
In my many years I have not seen a definitive answer, some believe it to be a 'quirk bug' that does not demand the time Microsoft to sort out.
It has something to do with the cell referencing the upper left cell of a 'merged group of cells'.
It is particularly troublesome when dealing with blocks that are both merged rows and columns if you are using data manipulation on a sheet.
You will notice @KOKOSEK has de-merged some.
As small recompense for my earlier 'erring' I have added the totaliser (formatted custom [h]:mm) this overcomes the 24 hour limit of hh:mm
And cosmetically cleaned up the daily total in an attempt to suppress the '########' fault.
torachan.