253. What is a number?
254. How many foundational cardinal numbers are there?
255. What are the rulings of single numbers with the masculine or feminine word they are numbering?
256. What is the ruling of a compound number with the word it is numbering?
257. Are compound numbers declinable or indeclinable?
258. What are the rulings of decimal and coupled numbers?
259. What is the ruling of the word that comes after a number?
260. What is the case of a numbered word?
253. A number indicates the amount of the numbered thing; cardinal, or the order of it; ordinal.
254. There are four types of cardinal numbers: singular, with are one to ten, a hundred and a thousand, compound, which are eleven to nineteen, decimal, which are twenty to ninety by tens, and coupled which are twenty one to ninety nine (not including the decimals).
255. Singular cardinal numbers: when between three and ten accept the feminine tā' when the numbered object is masculine and do not accept it when the numbered object is feminine, for example:ثلاثةُ رجالٍ و ثلاثُ فَتیَاتٍ, the numbers one and two are masculine with a masculine numbered object and feminine with a feminine, for example: رجلٌ واحدٌ و امرأتانِ اثنتانِ, the numbers one hundred and a thousand are the same when the numbered object is masculine or feminine, for example: مائة صبيٍ و ألف قتاةٍ.
256. Compound numbers: with a masculine numbered object - the first part is feminine and the second masculine, for example: ثلاثةَ عَشَرَ رجلاً, with a feminine numbered object - the first part is masculine and the second feminine, for example: ثلاثَ عَشرة امرأةً. Eleven and twelve are exceptions; they are masculine with a masculine numbered object and feminine with a feminine, for example: اثنا عَشَرَ رجلاً.
257. Both parts of a compound number are indeclinable with a fathah except the number eleven and twelve, whose first part is declinable as a dual form whose nūn is erased when prefixed and its second part is indeclinable, for example:عِندي اثنا عَشَرَ قلماً و اثنتا عَشرَةَ دَواةً. There are two points to pay attention to: One, the shīn of the number ten (feminine form) has a fathah when it is singular and a sakūn when it is in a compound number. Two, the shīn of the number ten (masculine form) has a sakūn when it is singular and a fathah when it is in a compound number.
258. Decimal numbers remain in the same form when used with a masculine or feminine numbered word, for example:عِشرونَ رجلاً و عِشرونَ امرأةً. The first part of coupled numbers becomes masculine and feminine like singular numbers and the second part is the same with masculine or feminine numbered words like decimal numbers.
259. There are two cases for the noun that comes after a number: genitive, in the plural form between the numbers three and ten, for example:أربعة رجالٍ, or in the singular form with the numbers one hundred and one thousand, for example:مائة رجلٍ, or accusative in the singular form between the numbers eleven and ninety nine, for example: خمسة عَشَرَ قَلماً.
260. The numbered word is always singular except if it is in the genitive case after a number between three and ten, where in this case it is plural, as you have seen.