This article explains the keyboard shortcuts present in RadNumericUpDown as well as the properties that can be used for keyboard navigation.
In order to change the value without clicking on the repeat buttons of the control, you can also use the following keyboard shortcuts:
MouseWheel: whenever a RadNumericUpDown is focused you can change its value by using the mouse wheel. The step change will be equal to the value of SmallChange.
PageUp: increments the value by one step equal to LargeChange.
PageDown: decrements the value by one step equal to LargeChange.
Up: increments the value by one step equal to SmallChange.
Down: decrements the value by one step equal to SmallChange.
TabNavigationExtensions.IsTabStop attached property indicates whether RadNumericUpDown is included in the tab navigation cycle. Example 1 illustrates how to set that property in order to exclude the control from the tab navigation. The property is available since R3 2016.
[XAML] Example 1: RadNumericUpDown with TabNavigationExtensions.IsTabStop
<telerik:RadNumericUpDown telerik:TabNavigationExtensions.IsTabStop="False" />