While I was fixing my Razer Blackwidow keyboard, I want to keep my PC operating, so I tried to connect the Apple Wireless Keyboard, the pairing process stopped because the Apple Wireless Keyboard can not detect the key entered.
I found a solution, here it is:
In Windows 10’s bluetooth settings (can be found in system tray), click on the icon and then click “Add Bluetooth Device”.
Then, on the Apple Wireless Keyboard, hold down Command + W, while Windows is searching for bluetooth devices.
Then (hopefully) after it finds your Keyboard, it will want to pair with it. Follow the on screen prompts and eventually you will have to type in a pairing code.
Type in this code (shown on the screen) and hit Return. If no code showing, type 123456.
Your Keyboard should successfully pair with Windows 10 via Bluetooth