Calcule os produtos; a) ( +2 ) . ( +9 ) = b) ( +8 ) . ( -5 ) = c) ( +3 ) . ( +15 ) = d) 0 . ( -19 ) = e) ( +2 ) . ( -9 ) = f) ( -6 ) . ( +11 ) = g) ( +5 ) . ( -16 ) = h) ( +11 ) . 0 i) ( -2 ) . ( +21 ) =