Whichth hour is it?

In Esperanto this is how you’d say it’s 3 o’clock:

estas la tria (horo)
literally: it’s the third (hour)

Which I think is nice and simple.

The little interesting thing today, is in asking the question “what time is it?

kioma horo estas? 
what time is it?

Specifically kioma is the cool bit. It comes from kiom which is a correlative word (see previous post), meaning “how much/many”. I just like the simplicity of why the “a” is there:

I think the PMEG’s explanation is pretty neat:

You use kiom to ask for:

unu, du, tri… 
one, two, three…

And you use kioma to ask for:

unua, dua, tria...
first, second, third…

So “kioma horo estas” is like “which-th (or even “how many-th”) hour is it?”, to which you reply with “the fourth”! 

EDIT:

I just found why “which-th” was so natural to my brain. I had indeed read it before. Check out this page of “Being Colloquial in Esperanto”. It has a neat little sentence that is ambiguous in English:

which of his sons are you?

Is the answer “the third” or “charles”?

But in Esperanto kioma asks for “whichth” (the third): which one are you in order?

And kiu asks for “which” (charles): which son are you?