Help us caption and translate this video on Amara.org: http://www.amara.org/en/v/B2ue/ Esercizi: http://www.khanacademy.org/exercise/properties_of_numbers_1 Traduzione in Italiano del video Associative Law of Addition http://www.youtube.com/watch?feature=player_embedded&v=oTKVXJ7TcbA http://www.khanacademy.org/math/arithmetic/number-properties/v/associative-law-of-addition