By turning on Mouse Keys, you are able to control the mouse pointer with the numeric keyboard. More specifically speaking, you can use the number keys (i.e. 1, 2, 3, 4, 5, 6, 7, 8 and 9) on the numeric keyboard instead of the mouse to move the mouse pointer around the screen. For your better reference, this article specially illustrates how to turn on Mouse Keys on Windows 10.
Video guide on how to turn on Mouse Keys in Windows 10:
Method 1: Turn Mouse Keys on in Control Panel.
Step 1: Get into Control Panel.
Step 2: Select Ease of Access.
Step 3: Click Change how your mouse works.
Step 4: In the window titled Make the mouse easier to use, select Turn on Mouse Keys and tap OK.
Method 2: Turn on Mouse Keys in PC settings.
Step 1: Enter PC settings.
Step 2: Open Ease of Access.
Step 3: Click Mouse to access its settings, tap the switch under the setting called Use numeric keypad to move mouse around the screen to turn it on.