Six = 6 = Seis?
Yes, I hear you say. Of course! There is more to be said. There are idioms that use the word “six”.
If a person is “at sixes and sevens” that person is confused, and if things are at sixes and sevens then those things are not in order, or speaking frankly (hablando francamente), the situation is a mess (un lio). So Mr. Barnier, the Brussels/Brexit EU negotiator “is all at sixes and sevens” meaning that he is confused and unsure what to do.
If something is “six and half a dozen” (da igual o da lo mismo) it means that it is the same to you. So you might say it is “six and half a dozen” if we go to Berlin or Cologne for our holiday. This means that you think the locations for your holiday are similar.
Someone might try and “knock someone for six” (dejar pasmado a algn). If you said that “the news about Brexit “knocked Mr. Morales for six” (la noticia sobre Brexit dejó pasmado Señor Morales) it means that the news shocked him or that he was very surprised.
So, have you ever been at sixes and sevens? Probably.