Mi eĉ ne memoras vian telefonnumeron.

Eĉ ne means not even.

• eĉ = even
• ne = not

Putting them together gives emphasis: I do not even remember your phone number.

In Esperanto, eĉ ne is a very common combination. It works much like English not even.

Memoras has the ending -as, which marks the present tense.

So mi memoras means I remember.

That may feel a little different from English, because English sometimes uses I don't remember to talk about a present state, even if the thing remembered is from the past. Esperanto does the same here: Mi ne memoras = I don't remember.

If you wanted I didn't remember, you would use memoris instead:

• Mi ne memoris = I didn't remember

Because telefonnumeron is the direct object, and in Esperanto direct objects usually take -n.

• telefonnumero = phone number
• telefonnumeron = phone number (as a direct object)

The word vian also gets -n because via is a possessive adjective, and adjectives agree with the noun they describe in case and number.

So:

• via telefonnumero = your phone number
• vian telefonnumeron = your phone number (as a direct object)

This agreement is very important in Esperanto.

Because via is describing a noun that is in the accusative.

In Esperanto, possessives like mia, via, lia, ŝia, nia, ilia behave like adjectives. That means they match the noun they go with.

Since telefonnumeron has -n, via must also take -n:

• via numero = your number
• vian numeron = your number (direct object)

So vian is not a special possessive form by itself; it is just via with the accusative ending added.

It is a compound word:

• telefon = telephone
• numero = number

Together:

• telefonnumero / more commonly spelled as one compound telefonnumero = telephone number / phone number

The double n appears because one part ends in n and the next begins with n:

• telefon
  • numero → telefonnumero

Then the accusative -n is added at the end:

• telefonnumero
• telefonnumeron

So the last -n is grammatical, while the earlier nn comes from the compound itself.

Esperanto has:

• la = the
• no separate word for a/an

In this sentence, la is not needed. With possessives, Esperanto often does not use la unless there is a special reason.

So:

• vian telefonnumeron = your phone number

That is completely normal. Saying la vian telefonnumeron would usually sound unnatural here.

The given order is very natural:

• Mi = subject
• eĉ ne = emphasis + negation
• memoras = verb
• vian telefonnumeron = object

Esperanto word order is more flexible than English because the endings show grammar clearly. So some rearrangement is possible, but it can change the emphasis.

For example, the original sentence naturally emphasizes the idea of not even remembering.

A learner should usually stick with the standard order until they are comfortable with how emphasis works.

No preposition is needed here.

Memori directly takes an object, just like English remember in a sentence such as I remember your name.

So:

• Mi memoras vian nomon = I remember your name
• Mi ne memoras vian telefonnumeron = I don't remember your phone number

That is why telefonnumeron appears directly after the verb, with the accusative -n.

A simple pronunciation guide:

Mi eĉ ne memoras vian telefonnumeron.
mee etch neh meh-MO-rahs VEE-an teh-leh-fon-noo-MEH-ron

A few useful notes:

• ĉ sounds like ch in church
• stress in Esperanto normally falls on the second-to-last syllable
• so you get:
  • meMOras
  • VIan
  • telefonnuMERon

Esperanto pronunciation is very regular, so once you learn the sounds, sentences like this are quite predictable.