Help with formula

[Marty the Hat]

Hi, I have a feeling there is a very basic, simple answer to this but I can't figure it out...

I have a sheet that details values for each month, there is a formula in the sheet in cell N3 that currently calculates the difference between the values in cells I3 and H3. What I want to do is modify the formula so that when a value is entered in cell J3 the formula automatically updates and calculates the difference between J3 and I3 and so on each time a new entry is made. I think I need something in my formula that identifies when a cell is the last cell in the row to have an entry (not be null).

Any help greatly appreciated

 

[shrivallabha]

What happens if someone directly fills cell K3 and leaves J3 blank?
What happens when there's only one cell e.g. A3 is filled.

 

[Marty the Hat]

Hopefully that would never happen but if it did the formula would just need to calculate the difference between the most recent value and the last populated value.

 

[shrivallabha]

You can use logic like
=INDEX(A3:L3,1,COUNTA(A3:L3))-INDEX(A3:L3,1,COUNTA(A3:L3)-1)
assuming you have at least two cells filled all the time consecutively. I edited my post little late, what will happen when only cell A3 is filled?

 

[Marty the Hat]

Thanks Shrivallabha that works perfectly!, doesn't matter if only A3 is filled as this will only be used to compare two values, never when only one is available.