QGIS filling more than one column in data attribute table at once

I would like to fill up the columns, which values are the same. There are 2 columns (in future it can be more).
Unfortunately, I’ve encountered a problem, described in the image below. I don’t know really how to solve it.

I’ve marked the stuff I can put in. The column data should be integer here. I don’t understand why it doesn’t work.

I found the similar problem under the thread below:

QGIS Field Calculator Error for String values

which applies to strings. Since I quote my number it, the quote disappears and problem remains the same.

Is there any way to use the field calculator for more than one column at once?