How do you form plural nouns with numerals?

When forming plural nouns with numerals, there are a few rules to follow:

1. If the numeral is one (1), the noun remains in its singular form. For example, "one book" or "one car."

2. If the numeral is any number other than one, the noun usually takes the plural form. For example, "two books" or "five cars."

3. If the numeral ends in a digit from 2 to 9, the noun takes the plural form. For example, "three books" or "eight cars."

4. If the numeral ends in a digit from 0 or 1, the noun usually takes the singular form. However, there are exceptions to this rule. For example, "ten books" or "twenty-one cars."

5. If the numeral is a fraction or a decimal, the noun usually takes the singular form. For example, "half an apple" or "0.5 kilograms of sugar."

6. If the numeral is a whole number followed by a fraction, the noun usually takes the plural form. For example, "two and a half hours" or "three and three-quarters cups."

It is important to note that there are some irregular plural forms that do not follow these rules. For example, "one child" becomes "two children" and "one mouse" becomes "two mice."

Overall, forming plural nouns with numerals requires understanding the general rules and being aware of any irregular forms.