Using datediff in a expression tag

Hello, I’m trying to get the difference between 2 dates using datediff() function in an expression tag but the result is not like it supposed to be. Attached the picture. I get the result but also with characters “yyyy-mm-dd” that I don’t need.

Is there a way to just get the number??


Clear the number format on the tag - I’m guessing you originally had Fecha_Diff created as a Date datatype.