IF Cell is Blank, Show Blank, Otherwise do Sum - Not Working

Hello,

I am having trouble with a simple IF formula. Please see attached file with my data. I made the cell where I am having trouble with the formula in yellow.

If the cell in column C is empty I would like my formula in F column to stop summing and return "" or space or "-", but if there is a value in column C it should do the sum, just like in the formulas above it. I would add this formula in all cells in col F of course (except the first cell).

I think that normally the formula should look like this:
{ =IF (C10="";"";F9+C10-D10) }
but I also tried this
{ IF (C10="";"";F9+C10-D10) }
and this:
{ IF C10="" "" F9+C10-D10 }
and this:
{ IF (C10)="" "" (F9+C10-D10) }
and this:
{ IF {C10}="" "" {F9+C10-D10} }

They either show a blank result when it should be a sum, or they show "Syntax error".
My regional settings are with semicolon, but I also tried with comma and got the same results.

I've tried several others I can't even remember anymore, to no avail.

I hope this is possible and someone can help me.

Please attach excel file, not Word document.
Can't help you without it.

This question is posted under the Word section because formulas can also be used in Word.

I know how to do it in Excel, but I need this to work in Word unfortunately.

*****

The formula below works if I put 0 instead of "" after =C10.
For some reason it won't work if in the formula I try to compare C10 to a blank ("").

This does not work: { IF { =C10 } = "" "" { =F9+C10-D10 } }
This works: { IF { =C10 } = 0 "" { =F9+C10-D10 } }

The problem is I have 0 on APR row and the formula in F on that row will be 0 and then all the following results will be wrong.
Also I might have more consecutive zeroes, so using AND inside IF won't be a solution.

Does anyone know how I could compare C10 with empty cell ("") instead of 0?

After more googling during the weekend, including for various alternative ideas (eg. add a space in the cell with 0 while leaving the blank cell blank), I found out that one can't refer to a blank cell in Word. Quoting user Cindy M from wordbanter in a post from 2005: "you can't test for an "empty" cell, because a cell in Word is NEVER empty. It always holds the end-of-cell marker (combination of a paragraph mark, plus a range that contains a pointer to the cell formatting and structure information in the document's binary structure). You can test for a value of 0, however. If the cell contains nothing, it will return 0."

In my case, as stated in the post above, referring to zero doesn't help because I have zero values in cells and still need the formula to calculate and show the result for those cells.

I tried to use the end-of-cell marker character (char 0164) but I haven't found a syntax to use such characters in Word formulas.

*****

However, I found an acceptable alternative that works for me - might not for others. A rather "unorthodox" alternative. I'll explain why.

Since I can't find a formula to return the desired blank cell in column F in case the cell in column C is empty, I thought of formatting the text in column F and make text white in F if cell in C is empty.

If you downloaded my file from post #1 you noticed that I have bookmarks for columns C and D for each month.
I have to complete some Word documents monthly and do some math inside them.
So I use HTA (HTML for Applications) combined with VBA code to open .doc files, insert values, refresh formulas, save and close .doc files with just 1 click after typing the desired values in the HTA textboxes.

For the file I attached in post #1 I made the font color in column F in white for months AUG+SEP+OCT+NOV+DEC (these are the cells corresponding to column C empty cells).

For this to work I also created bookmarks for cells in column F, like T1_jan_INV, T1_feb_INV and so on until T1_dec_INV.
I added a few lines of VBA to my HTA file so that when I enter values in bookmarks for one month it also colors the text in black for that month in INV column.

Eg. in the file from post #1
- I added bookmarks for cells in column F
- AUG is empty and the text in INV column is white (the result of the formula is normally not visible and won't be visible in case I print the document)
- I use HTA to insert values in bookmarks T1_aug_1 and T1_aug_2 (columns C and D cells for aug month)
- the few lines of VBA I added will color the text in the corresponding bookmark - which is T1_aug_INV - in black, thus making my sum visible

*****

I'm still open to any suggestions on a way to solve my issue from within the formula.
This might also help others who don't use code to insert values or don't want VBA to color text.