Custom Room Numbers

Hello.
In our country room numbers are a little bit diffrent from the component.

we use 1+1 , 2+1, 3+1 , 3+2 etc. which means small room numbers + big room numbers

bath and bedroom numbers are never mentioned.


so I want to change room number ( $nroom) to a custom array that I will create like above. and I want dropdown search boxes to be seen as mentioned. is that possible