What are the two part of noun by numerical expression?

It seems like you're asking about how nouns are categorized based on how many they represent. Here's a breakdown:

1. Singular Nouns: These refer to one individual or item.

* Example: *dog*, *book*, *flower*

2. Plural Nouns: These refer to more than one individual or item.

* Example: *dogs*, *books*, *flowers*

Important Note: The question is a bit tricky, because while we could say there are two parts (singular and plural), it's more accurate to say that singular and plural are two forms of a noun, not two parts of a noun.

Let me know if you have any other questions about nouns!