Enter and delete data in a number field?

Can someone tell me how to enter data in an empty number field?
I doesn’t work when I want to enter a value via a form in a number field. When I use a method to enter a value in the same field it works fine.
When a number field contains a value I can’t clear the field via the form.

Alexander

Check if your field property “editable” is unchecked?
Otherwise , do you get any error message?
What are you exactly typing in the field?
How does your method look like?