У книзі шістдесят сторінок.

Because after у here, Ukrainian uses the locative case to mean in the book.

• книга = book (dictionary form, nominative)
• у книзі = in the book (locative)

So the noun changes form:

• книга → книзі

This is very common after prepositions like у / в when they mean in.

Yes. У and в often both mean in.

So these are both possible:

• У книзі шістдесят сторінок.
• В книзі шістдесят сторінок.

The choice between у and в is often made for easier pronunciation and smoother sound, not because the meaning changes. Ukrainian tries to avoid awkward clusters of consonants or vowels.

Here, у книзі is a very natural choice.

In the present tense, Ukrainian often omits the verb to be.

So instead of saying something like In the book there are sixty pages, Ukrainian simply says:

• У книзі шістдесят сторінок.

This is completely normal. The idea of there are is understood from the sentence structure.

If you translated it very literally, it would be something like:

• In the book sixty pages.

But in natural English, of course, you would say There are sixty pages in the book or The book has sixty pages.

Because after шістдесят (sixty), Ukrainian uses the genitive plural form of the noun.

The noun is:

• сторінка = page

Its forms are:

• сторінка = nominative singular
• сторінки = nominative plural / also some other uses
• сторінок = genitive plural

After numbers like 5, 6, 7 ... 60 ... 100, Ukrainian normally uses the genitive plural:

• п’ять сторінок = five pages
• десять сторінок = ten pages
• шістдесят сторінок = sixty pages

So сторінок is required here.

This is one of the most important number patterns in Ukrainian:

• 1 → usually nominative singular

  • одна сторінка = one page

• 2, 3, 4 → usually a special plural form that looks like nominative plural

  • дві сторінки = two pages
  • три сторінки = three pages
  • чотири сторінки = four pages

• 5 and higher → usually genitive plural

  • п’ять сторінок = five pages
  • шістдесят сторінок = sixty pages

So шістдесят сторінок follows the normal 5+ pattern.

Yes, absolutely.

• У книзі шістдесят сторінок. = There are sixty pages in the book.
• Книга має шістдесят сторінок. = The book has sixty pages.

Both are natural, but they focus slightly differently:

• У книзі... focuses on what is in the book.
• Книга має... focuses on the book as the thing that has something.

In many situations, they are basically interchangeable.

Not completely. Ukrainian word order is fairly flexible.

The neutral version here is:

• У книзі шістдесят сторінок.

But you may also hear:

• Шістдесят сторінок у книзі.

This can shift the emphasis a bit. The original sentence sounds like a normal, neutral way to state the fact.

Because Ukrainian uses case endings, word order often helps express focus or emphasis rather than basic grammatical roles.

This is the regular locative-type change for many feminine nouns ending in -а.

For книга:

• remove -а
• add -і
• also, the consonant changes: г → з in this form

So:

• книга → книзі

This kind of consonant alternation happens in some noun forms in Ukrainian and is something learners gradually get used to.

Сторінок is genitive plural.

In this sentence:

• у книзі = locative singular
• сторінок = genitive plural

So the sentence contains two different case forms:

1. книзі because of the preposition у
2. сторінок because of the numeral шістдесят

This is a good example of how Ukrainian grammar often depends on both prepositions and numbers.

You would change the noun form according to the number:

• У книзі одна сторінка. = There is one page in the book.
• У книзі дві сторінки. = There are two pages in the book.
• У книзі три сторінки. = There are three pages in the book.
• У книзі чотири сторінки. = There are four pages in the book.
• У книзі п’ять сторінок. = There are five pages in the book.

So the pattern is:

• 1 → сторінка
• 2–4 → сторінки
• 5+ → сторінок

That is exactly why шістдесят сторінок looks the way it does.