Adding numbers within a single cell

Hey everyone - I was wondering if it’s possible to have Calc automatically add numbers as they are entered within a single cell. For example, I have “4” in a cell, then I later come back, click on that cell, and type “5”. Would it be possible to have Calc display “9”? Then if I came back again and clicked on it, typed “3”, Calc would display “12”, etc. I have a feeling this isn’t possible, but figured it couldn’t hurt to ask. Thanks!

Code your initial entry in the cell as “=4”. When you return to add the 5, edit the cell (just hit F2) and append “+5” to the “=4”, giving “=4+5”. Hit enter and the resulting “9” will be displayed.