Q: Is there another way to pair the wireless keyboard other than a number passkey?

I turned my iMac on to find out it's not paired with the wireless keyboard anymore, and I don't know why. I tried pairing it, but most of the number keys have not worked for a while, so it's impossible. I know the obvious answer is "get a new keyboard" but I was just wondering if there is any other way to pair them.

Thanks!