Build a Program for reading Digit through Camera

Hi , one of my customer who is doing public auctions for properties, vehicles, land and various items , the auction happens on certain days at a certain place (usually meeting halls in hotels), and any people can come and bid for the auction and final highest bidder will be the winner. The bidding increment amount also fixed, means increase by 50000 , etc.. Currently we have deployed a Realtime Program build for tracking the bidding and a web page that display the current highest bidder and amount on a projector, every bidder is registered in the system at the entrance and provided a number plate starting from 1 and increasing sequentially as identity no, during the bidding, the bidder have to raise the hand with the number card, and we have an appointed person who will enter the bidder no and increasing the last bid by the fixed amount, every works perfect as I described, Now we are planning to make the bidding process more smart, that means, rather an appointed person entering the number in system when a bidder raise the hand, can we automate it by reading the digits through any cameras, for this we donot have any technology requirement, can use any possible technology, but we want the program to pass the read data to an specific web api, I am not sure whether this need AI or can be done with any other technology