Hello,

We, Egyptians always use كتابين - regardless of the grammatical case - and we pronounce it "ketabein" and NOT "ketabayn" like in MSA

In MSA, the grammatical cases go like this:

- In Nominative case the dual is formed by adding ـان -an

Example: كتابـ ـان ketab-an

- In both the Accusative and Genitive cases the dual is formed by adding ـين -ayn

Example: كتابـ ـين ketab-ayn

To expand on what Akram has said, there are no case endings in colloquial Arabic, and as such the dual and plural forms have become one each rather than the different forms for the nominative and accusative/genitive cases that exist in MSA. In other words, neither the dual nominative nor the plural nominative forms in MSA exist in colloquial Arabic.

Example:

MSA: مهندسان (two engineers, nominative); مهندسَين (two engineers, accusative or genitive); مهندسون (more than two engineers, nominative); مهندسِين (more than two engineers, accusative or genitive).

Colloqual Arabic: مهندسَين (two engineers); مهندسِين (more than two engineers).

You can tell whether it’s a dual or plural by the vowel sound. The dual is muhandisAYn and the plural is muhandisEEn.

I am not familiar with any dialect that has retained the nominative suffixes.

Yes you are right

book  singular كتاب   

كتابان او كتابين  2books dual 

كتب books plural 

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