Help us caption and translate this video on Amara.org: http://www.amara.org/en/v/B2xm/ Esercizi: http://www.khanacademy.org/exercises?exid=subtraction_4 Traduzione in Italiano del video Level 4 Subtraction http://www.youtube.com/watch?v=omUfrXtHtN0 http://www.khanacademy.org/video/level-4-subtraction?playlist=Arithmetic Help us caption & translate this video! http://amara.org/v/B2xm/