If it's IR, your device needs to have IR command for each number. I don't think any devices have that. If you have a hub, I believe you can use it to assign a keyboard button for each remote button. In that case, use your Harmony Hub to add each keyboard number.

Needless to say, if you have a keyboard paired/attached, you can use the numbers on that.

Then the app would have to be programmed to accept the numbers for that purpose which I don't think it is.

Don't know which Harmony you are using but with the Hub you add a windows keyboard device to your profile. Even the guide button on the remote works- it starts Live Channels when you hit the button.

is this on a nvidia shield?