example2.kv

BoxLayout:
    orientation: 'vertical'
    BoxLayout:
        id: fields
        orientation: 'vertical'
        size_hint: (1.0, 6.0)
    BoxLayout:
        orientation: 'horizontal'
        Button:
            text: 'Add Field'
            font_size: sp(24)
            on_press: app.add_field()
        Button:
            text: 'Remove Field'
            font_size: sp(24)
            on_press: app.remove_field()
    Label:
        id: result
        text: f'Smallest Positive: {app.smallest_positive}'
        font_size: sp(24)

<Field>:
    orientation: 'horizontal'
    Label:
        text: root.label_text
        font_size: sp(24)
    TextInput:
        id: input
        multiline: False
        write_tab: False
        font_size: sp(24)
        on_text: app.update()