Calc: How to format a range of cell?

Select A2:A6
Format > Cells > Numbers tab > Number > General > OK

I would like to convert format of date in some cells of such range into number format.

Why does Calc do nothing?

Format range is unable.ods

What about Format > Cells > Number> -1235 > OK ?

Dear @JohnSUN,

Thank you.

It works.

Is it true that all cells in such range must be all in date format ?

Resolved by:
Format > Cells > Numbers tab > Number > -1235 > OK