Numbers – date cell set to last day of the month

I believe Insert > Date & Time (and its two companions) are intended for use in headers and footers. These are available after choosing File > Print. When used there, the inserted date can be clicked for a little popup formatter and button to manually reset the time to now.

The feature you want, an auto-generated NOW cell that does not change, is apparently not available.

Option A: Put the NOW function into a cell somewhere. It shows the current time. Copy the cell, then Edit > Paste Formula Results into the cell you want to have the unchanging time.

Option B: Use a general macro app (like the amazingly capable Keyboard Maestro) to generate your date/time text and paste it into a cell.

In both cases, choose the date and time formats you want on the final cell.

(Numbers 3.5.3 used for this answer)

I offer this answer only because at least it provides a workaround, albeit a slightly manual one.

Assuming that B1 is the cell that needs to have the date and time auto-populated when cell A1 is filled in, enter this formula in cell B1:

IF(ISBLANK($A1),"",NOW())

Now, when the time comes that cell A1 is filled in, cell B1 will auto-populate with the date and time.

However, to prevent cell B1 from updating if/when cell A1 is edited again, you now need to do as follows:

1. After B1 is populated, select cell B1
2. Use commandC (or go to Edit > Copy) to copy the cell
3. Use shiftcommandV (or go to Edit > Paste Formula Results)
4. Now the formula in cell B1 is replaced with the calculated value only, thereby meaning it will no longer calculate in future

NOTES:

In case this is useful for anyone else trying to come up with an answer, I also thought of:

• using an AppleScript script to replicate the above, but then realised that using a script would be no quicker that just using the Copy/Paste functionality within Numbers.

• creating an Automator service and then allocating a keyboard shortcut to that, but that too would be no quicker as you'd still need to select the cell, so using the built-in shiftcommandV shortcut is no slower than using a customisable shortcut.

Regardless, someone more adept at AppleScript may think of a more elegant solution that works with Numbers to achieve the OP's goal.