As part of our first unit of the year in Math we are working on Addition and Subtraction concepts. I found two games that I thought would help students with Missing Numbers. Check out these great games! I had a hard time not sitting and playing... I love my Math!
http://www.sheppardsoftware.com/mathgames/matching/AdditionX.htm
http://www.fuelthebrain.com/Game/play.php?ID=1