a) \( 56d{m^2} = \dfrac{{56}}{{100}}{m^2} = 0,56{m^2}\);
b) \(17d{m^2}\;23c{m^2} = 17\dfrac{{23}}{{100}}d{m^2}\)\( = 17,23d{m^2}\);
c) \(23c{m^2} = \dfrac{{23}}{{100}}d{m^2} = 0,23d{m^2}\);
d) \(2c{m^2}\;5m{m^2} = 2\dfrac{5}{{100}}c{m^2} = 2,05c{m^2}\).