Here is a simple example
1. When you start the task select A1 and touch CNTRL-SHIFT-;
2. When you complete the task select A2 and touch CNTRL-SHIFT-;
3. In A3 enter:
=A2-A1
4. NECESSARY TRICK:
select A3 and
Format > Cells > Time > 13:30

Signature
Gary''s Student - gsnu200726
> Hi,
>
> Is there any add-ons which will enable me to measure the time needed
> for work as Slimtimer?
>
> Best.