You can press left ALT + left SHIFT + NUMLOCK keyboard shortcut to turn on or off this feature. Once activated, the Mouse Keys icon will appear on the taskbar. You can then navigate in different directions using the numeric keypad's arrow keys. If it feels too slow at first, that's because most of us use the mouse so extensively that it makes us handicapped without it.
As this Microsoft Support article informs almost all keys in the numeric keyboard can mimic some feature of the mouse
By memorizing & practising these keyboard shortcuts alongwith those of popular applications, you may be able to improve your productivity & possibly dazzle those around you with your keyboard skills.Press the 5 key for a single mouse click and the plus sign key (+) for a double-click. To drag an object, place the pointer on the object and press the INSERT key to begin dragging. Press DELETE to release the object. To drag an object, place the pointer on the object and press the INSERT key to begin dragging. Press DELETE to release the object.