Number sense game

One of my favorite games to play with my students to reinforce number concepts is what I call Number Twenty Questions.  I use the interactive 100 board on my Smartboard Notebook software but I've used my regular 100 board also.  I start the game by secretly choosing a number.  I then have students ask me yes or no questions about my  number.  I try to teach them what types of questions to ask.  For example, does your number have two digits?  Is your number even?  I just get them started at the beginning when I first teach the game but then the students get very creative. This game could also be played with a 200 or a 300 chart.  I do not have an interactive one of either of those though.  Using my interactive board, I will color out numbers as we eliminate them because that way students are connecting their question with the numbers being colored out.  I also make a rule that students cannot guess my number until there are 6 or less numbers left on the board.  The student who guesses my number correctly gets to pick the next secret number.  The kids love this game and will beg to play.  Here is a screen capture of my 100 board. I was going to ask if you could guess what questions had already been asked but I just realized I forgot to block out a whole column. (The 9  column)  OOPS! Sorry.