Відмінювання числівників

They are not frozen

At A1 numerals appeared only in the nominative, where they govern the noun. Once the phrase itself moves into another case, the numeral moves with it - and so does every word of a compound.

Numerals from five upwards decline like feminine nouns in -ь: one form, пяці, covers the genitive, dative and locative.

Every word of a compound

This is the part that gets skipped:

• з дваццаццю пяццю рублямі - with twenty-five roubles
• каля ста пяцідзесяці чалавек - about a hundred and fifty people

In careless speech people freeze the numeral and decline only the noun. In writing that is an error, and it is the single most reliable sign of an unedited text.

Адзін declines like an adjective

адзін, аднаго, аднаму, адным; feminine адна, адной, адну. It agrees with its noun in gender, number and case throughout.

Два has an animate accusative

Like nouns: бачу два сталы but бачу двух сяброў.

Ordinals are simply adjectives

They decline like новы, and in a compound only the last word is ordinal and only it declines: у дзве тысячы дваццаць пятым годзе.

So the two systems behave in opposite ways: in a cardinal every word moves, in an ordinal only the last one does.