Manually edit the cell without delete the original formula

Hi,

I have a cell with formula which will call up a part number.

But in some case, i want to allow user to manually enter new part number in the respective cell. How do i make it work?

If manually enter a number, the formula will gone.

use two columns.
First with formula, second manually.

If second value is blank then use formula.

any solution if i dont want to create any temporary cell?
This is because the cell is used by other user, just like a form.

You can't overwrite formula and expect that formula exist.
What would be meaning of overwritting then?!

i am doing the formula to be used in the document controlling system.
For instance:
Cell A1 has drop down list: NEW, CURRENT, REPLACEMENT
Cell A2 is a empty cell with formula and i need it to allow manually edit
Cell A3 has a data

Cell A2 has a formula to do the following:
i) IF A1=REPLACEMENT, then A2=A3
ii) IF A1 IS BLANK or NEW or CURRENT, then A2 = ""
iii) BUT IF A1=REPLACEMENT & A2 IS NOT EQUAL WITH A3, then User will have to manually edit A2. After manually edit, the system will lookup data in another workbook.

Originally Posted by CYCHEAH

i am doing the formula to be used in the document controlling system.
For instance:
Cell A1 has drop down list: NEW, CURRENT, REPLACEMENT
Cell A2 is a empty cell with formula and i need it to allow manually edit
Cell A3 has a data

Cell A2 has a formula to do the following:
i) IF A1=REPLACEMENT, then A2=A3
ii) IF A1 IS BLANK or NEW or CURRENT, then A2 = ""
iii) BUT IF A1=REPLACEMENT & A2 IS NOT EQUAL WITH A3, then User will have to manually edit A2. After manually edit, the system will lookup data in another workbook.

As they was told it is not possible to have a formula in a cell and then write something in that cell.
Something is wrong in your logic:
You said:
i) IF A1 =REPLACEMENT, THEN A2 = A3
and
iii) BUT IF A1 = REPLACEMENT & A2 IS NOT EQUAL WITH A3 ????
How might happen if A1 = REPLACEMENT and thus A1 = A2?