Mi calculadora nueva funciona mejor de lo que esperaba en el examen de matemáticas.

In Spanish, descriptive adjectives often come after the noun, so calculadora nueva is a normal word order.

That said, mi nueva calculadora is also correct and probably sounds more natural to many speakers in everyday speech. The difference is subtle:

• mi nueva calculadora = a more neutral or flowing way to say my new calculator
• mi calculadora nueva = can sound a bit more contrastive, as if you are distinguishing it from an old one

So the sentence is grammatical, but the adjective position slightly affects the emphasis.

Yes. Mi nueva calculadora funciona mejor... is perfectly correct.

In fact, many learners will hear mi nueva calculadora more often than mi calculadora nueva. Putting nueva before the noun often sounds a little more natural when you are simply introducing the item. Putting it after the noun can feel a bit more specific or contrastive.

So both are possible; the choice is mostly about nuance and style.

Because in Spanish, machines, devices, and systems often funcionan.

So:

• La calculadora funciona = the calculator works / functions
• El móvil no funciona = the phone isn’t working
• La impresora funciona bien = the printer works well

Using trabajar here would sound wrong, because trabajar is mainly for people working, not for a calculator operating properly.

Because Spanish often uses comparative + de lo que + verb when comparing something to what was expected, imagined, believed, etc.

So:

• mejor de lo que esperaba
• más difícil de lo que pensé
• menos caro de lo que creía

This structure is very common and standard. Literally, it is something like better than what I expected.

You may sometimes hear mejor que esperaba in informal speech, but mejor de lo que esperaba is the safer and more standard choice for learners.

Here, lo que does not refer to a masculine noun. The lo is a neuter article, used for abstract ideas, situations, or things not named directly.

So de lo que esperaba means something like:

• than what I expected
• more literally, than that which I expected

In this sentence, lo que refers to the level or degree that the speaker had expected.

Because the sentence is referring to the speaker’s expectation, which is treated as a background mental state in the past.

The imperfect is very common for:

• thoughts
• expectations
• intentions
• ongoing background situations

So esperaba here means I was expecting or I expected in the sense of a prior expectation.

If you used the preterite esperé, it would usually be understood as I waited, not I expected, so it would change the meaning completely.

Because the structure makes that meaning clear.

In mejor de lo que esperaba, the idea is a comparison with an expectation, so esperaba means expected.

Compare:

• Esperaba el autobús = I was waiting for the bus
• Esperaba mejores resultados = I was expecting better results

So esperar can mean both to wait and to expect, and context tells you which one it is. In this sentence, it clearly means to expect.

After nouns like examen, clase, libro, or profesor, Spanish often uses de + subject name without the article.

So these are normal:

• examen de matemáticas
• clase de historia
• libro de física

Also, matemáticas is normally plural in Spanish when referring to the school subject:

• las matemáticas

But after de, the article is often dropped in this kind of label or category phrase. So examen de matemáticas is completely natural.

Because in Spanish, the subject mathematics is normally expressed as las matemáticas.

This is just the standard form of the word in Spanish, especially in Spain. It works like other school-subject names, even though in English maths/math behaves differently.

So:

• Me gustan las matemáticas
• Tengo examen de matemáticas mañana

Even when English uses a singular-looking word, Spanish may use a plural one here.

In normal reading, it most naturally tells you the context in which the calculator worked well: during/in the maths exam.

So the main idea is that the calculator performed better than expected in that exam situation.

However, because it is at the end, there is a slight chance of temporary ambiguity. If you want to make the time/context clearer, you could say:

• Mi nueva calculadora funcionó mejor de lo que esperaba durante el examen de matemáticas.

Using durante makes it very clearly mean during the exam.

That is a very good question. Grammatically, funciona is possible, but if you are talking about one specific finished exam, many speakers would more naturally say:

• Mi nueva calculadora funcionó mejor de lo que esperaba en el examen de matemáticas.

Using the preterite funcionó fits a completed past event better.

The present funciona can still work if the speaker is speaking more generally or using a vivid, conversational style, but for a single past exam, funcionó is usually the more natural choice.