Long distances are usually expressed in km, astronomical units (149.6 Gm), light-years (10 Pm), or parsecs (31 Pm), rather than in Mm, Gm, Tm, Pm, Em, Zm or Ym; "30 cm", "30 m", and "300 m" are more common than "3 dm", "3 dam", and "3 hm", respectively.
Así, as distancias moi longas adoitan expresarse en quilómetros, unidades astronómicas (149.6 Gm), anos luz (10 Pm) ou parsecs (31 Pm), máis que en Mm, Gm, Tm, Pm, Em, Zm ou Ym; tamén é máis común empregar "30 cm", "30 m" e "300 m" que "3 dm", "3 dam" e "3 hm".