DESAFÍO ARITMÉTICO

http://www.educaplus.org/play-284-Desaf%C3%ADo-Aritm%C3%A9tico-I.html

http://www.educaplus.org/play-285-Desaf%C3%ADo-Aritm%C3%A9tico-II.html

http://www.educaplus.org/play-286-Desaf%C3%ADo-Aritm%C3%A9tico-III.html