UpDown control looks by default like on the picture below. This control allow to store and modify integer value in specified range. It also can be assigned to Edit control to display the stored value and type it manually if needed. Below you can see the UpDown control assigned to Edit control. When you assign UpDown to Edit control, it set itself at the right of the Edit control.

UpDown control(widget) for integer numbers

When change by dragging is enabled (ChangeByDrag property is set to true), the change value is calculated as DragShift + DragScale * DragBaseDragBaseShift + DragBaseScale * δY. Where δY is how much mouse pointer is moved in up-down direction. Simply speaking, the formula means "the faster you move mouse pointer the bigger change is applied".