Sesenta es más que diez.

Because sesenta and diez are being treated as single numbers, not as groups of things. In Spanish, when you talk about a number as an idea or value, you use singular es.

• Sesenta es más que diez. = Sixty is more than ten.

But if the number is counting plural nouns, then the verb can be plural:

• Son sesenta personas. = There are sixty people.

So here, es is correct because the sentence is about the number itself.

Use más que when you are directly comparing one thing with another.

• Sesenta es más que diez.

Use más de when you mean more than before a number or quantity inside a larger phrase.

• Tengo más de diez libros. = I have more than ten books.
• Más de veinte personas vinieron. = More than twenty people came.

So in your sentence, sesenta is being compared directly with diez, which is why más que fits.

Here, que means than.

So:

• más que = more than

This is a very common comparison pattern in Spanish:

• más que = more than
• menos que = less than
• tan ... como = as ... as

In this sentence, que links the two things being compared: sesenta and diez.

The accent mark is required here. Más with an accent means more.

• más = more

There is also mas without an accent, but that usually means but and sounds literary or old-fashioned in most modern Spanish.

So in this sentence, you must write:

• más

not

• mas

Yes. Sesenta es mayor que diez is also correct, and it is especially common in math or more formal comparisons of numbers.

Both are understandable:

• Sesenta es más que diez.
• Sesenta es mayor que diez.

A useful difference is:

• más que = more than
• mayor que = greater than

For pure numerical comparison, many speakers would prefer mayor que in a mathematical context. But más que is still easy to understand.

A simple approximation is:

seh-SEN-tah es mahs keh dyes

A few pronunciation notes:

• sesenta → stress on the middle syllable: se-SEN-ta
• es → like ess
• más → mahs
• que → keh
• diez → roughly dyes (one syllable)

The z in diez is pronounced like s in Latin America, so it sounds different from Spain, where it would sound more like dyeth.

Spanish usually does not use an article before numbers when talking about them in a general way like this.

So:

• Sesenta es más que diez.

not usually:

• El sesenta es más que el diez.

You might hear el sesenta or el diez in special contexts, such as:

• talking about a specific number symbol
• school grades
• jersey numbers
• years, decades, or routes

But for a basic statement about numerical value, no article is needed.

Yes, absolutely. That is a perfectly correct way to express the same comparison from the other side.

• Sesenta es más que diez.
• Diez es menos que sesenta.

They mean the same thing overall, but the focus changes:

• first sentence focuses on sixty
• second sentence focuses on ten

Not really for numbers. Más grande is usually used for physical size, not numerical value.

For numbers, use:

• más que
• mayor que

So these are good:

• Sesenta es más que diez.
• Sesenta es mayor que diez.

But más grande que would sound odd if you are simply comparing numbers mathematically.

No, not in a normal sentence. Spanish needs the verb here.

• Sesenta es más que diez. = correct
• Sesenta más que diez. = incomplete as a sentence

You can leave out the verb in symbols or notes:

• 60 > 10

But when you say the full sentence in Spanish, es is necessary.