A math wizard has a bag containing the digits 0 through 9, and has used six of them to stick two different three-digit perfect squares on the foreheads of Ann and Ben. Both Ann and Ben know this fact, but each person can see only the other person's number. The wizard asks Ann, "How many of the digits remaining in my bag can you exactly tell me?"
Ann replies, "Two."
Ben then says: "I know my number."

There are 3 possible 3-digit numbers on Ben's forehead. What are they?