|re: "But using the cell formula that I found pressing CTRL+1..."|
By this I assume you mean a Custom Format, not a "cell formula".
A cell formula, at least to me, indicates something like =SUM(A1:A10) or
=IF(A1>10,"Yes","No"). What you seem to be discussing is a Custom Cell Format.
OK, so assuming that you are manually entering 3,5 in a cell, I am able to produce 3,5% in three different ways. (Please note that my system uses 3.5, not 3,5 so I am not testing your exact situation. That shouldn't matter, but I want to make sure that we include all factors.)
My three ways to get 3.5% displayed:
1 - Before entering 3.5, I clicked the % button. After entering 3.5 the display was 4%. I clicked the Increase Decimal button to display 3.5%. After that, all values entered show the percentage with a single decimal place.
2 - I selected a cell, pressed Ctrl+1, chose Number...Percentage...Decimal Places: 1. Entering 3.5 displays 3.5%. After that, all values entered show the percentage with a single decimal place.
3 - I selected a cell, pressed Ctrl+1, chose Custom and used 0.0% as my Custom Format. After that, all values entered show the percentage with a single decimal place.
If none of those methods work for you, we will need more detail into exactly what you are doing/trying to do. Keep in mind that we can not see your spreadsheet from where we are sitting, so in order to help us help you, you need to be very specific when explaining what you are doing/trying to do.
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