Advance an Excel formula via keyboard shortcut while in edit mode

Question

In order to incorporate the December number in the calculation, the SUM formula in the screenshot below must be "advanced" by one column. Is there a keyboard shortcut in Excel that will move this SUM function by one (moving to the right) once it is in edit mode to capture the value of the following column? I am seeking a keyboard shortcut to move the blue box to the right even though I am aware that I can do it with my mouse.

Naturally, I'm assuming the solution, if it exists, would be applicable to more Excel formulas than just SUM.

My Question:

While in Edit Mode in Excel, for any formula that requires an array for an argument (e.g. SUM, MIN, MAX, etc.), can I expand the existing array using a keyboard shortcut?

For example, in my screenshot below, I would like to expand EC64:EM64 to EC64:EN64 using just a keyboard shortcut. Is this possible? If so, how?

Answer 1

As requested, you can carry out the following actions with only your keyboard:

Press F2 when you are on the cell that contains your formula (EO64 in your example). Now that you are in Edit Mode, you should be able to see it at the bottom left of your Excel window. If it doesn't, right-click Excel's status bar and choose Cell Mode if it isn't checked.

Next, highlight the portion of the range you want to alter using Shift + left arrow (EM64 in your example).

Now press F2 again to activate Enter Mode. Use the arrow keys to move the "marching ants" into the cell you want to modify the existing range with (you'll notice that Enter Mode now changes to Point Mode). In your example, it appears to be EN64. Press Enter.

I hope this helps you.