Next, enter the following function in the cell under 01.01: = FAILURE (IF (MONTH (D5 + 1) = MONTH (D $ 5); D5 + 1; “”); “”))
With this function we say Excel in short that in the month of January does not appear at once a date from the month of February, and fade with IFFAILURE again unwanted error messages.
Repeat this function in the cell under the 01.02 again. But make sure that you also refer to the date in February, and not in January.
Now you can mark the cell with the 02.01, copy this at the lower right corner of the marker until the last day of January with the left mouse button pressed down. Then mark the first cell under “Day of the week” for January, and double-click on the left at the bottom right of the selection.
This will automatically fill all cells to the end.