These will probably show my ignorance but, 2 ques.

I've been asked to look at a spreadsheet and look at inhancing it. The
ques. I have to ask are these:

I want a formula to look at the prev. cell and if ther is a number in the
cell than to add 3 hrs (h:m) to an entered time and place that number in a
cell and add the number of hrs in decimal form in another cell.

Second thing is to not allow next entry (hr:m) if it is within the 3 hrs if
the above exists.

Does that make sense and/or can it be done?

Many thanks in advance,

Dom