Arabic Numbers Grammar

Summary: Rules governing the form and case of the counted noun (maʿdūd) in Arabic, which varies by number range.

Overview

In Arabic, the noun being counted — called the maʿdūd (المعدود) — changes form depending on the number. The rules are among the most complex in Arabic grammar.

Rules by Number Range — Complete Picture (as of Surah Yusuf Session 6)

Number Range	Tamyīz Form	Tamyīz Case	Example
1–2	No separate tamyīz — number itself is a صِفَة describing the maʿdūd	—	كِتَابٌ وَاحِدٌ, كِتَابَانِ (اثْنَانِ)
3–10	Plural	Majrūr	سَبْعَ لَيَالٍ وَثَمَانِيَةَ أَيَّامٍ
11–19 (compound, mabnī)	Singular	Manṣūb	أَحَدَ عَشَرَ كَوكَبًا (Yūsuf 12:4)
20–90 (الْعُقُود)	Singular	Manṣūb	تِسْعَةً وَتِسعِينَ نَعجَةً
100 (مِئَة), 1000 (أَلْف)	Singular	Majrūr	مِائَةَ شَاةٍ

99 — Why نَعجَةً Is Manṣūb, Not Majrūr

In تِسْعَةً وَتِسعِينَ نَعجَةً (99 ewes), نَعجَةً is manṣūb because it is the tamyīz of تِسعِينَ — the ʿuqūd (tens) component of the compound — not because of تِسْعَةً (the units digit, which alone would call for a plural majrūr tamyīz per the 3–10 rule). When units and tens are joined by وَ, the tamyīz takes its cue from the tens part.

أَلْفَاظ العُقُود — A Special Name for the Tens

The multiples of ten (عِشْرُون، ثَلَاثُون، …) follow the جَمع pattern and carry a special collective name: أَلْفَاظ العُقُود. There is a story behind why they are called this — left for a future session.

Singular Tamyīz Despite an English Plural Translation

إِنَّ عِدَّةَ الشُّهُورِ عِندَ اللَّهِ اثْنَا عَشَرَ شَهْرًا — "the number of months with Allah is twelve months"

شَهْرًا is singular even though the English translation says "months" — because it follows a compound number (11–19 family).

The 11–99 Rule in Detail

For numbers 11 through 99 (excluding round tens), the maʿdūd is:

Singular in form (not plural)
Mansūb (accusative) — functioning as a tamyīz (تمييز)

Example from the session:

Tisʿun wa ʿishrūna sūratan — "29 sūrahs"

Here sūratan is singular and mansūb. It appears in the discussion of how many sūrahs contain Muqattaat.

Compound Numbers 11–19 — الأَعدَاد المُرَكَّبَة

Numbers 11–19 are called أَعدَاد مُرَكَّبَة (murakkabah — compound): each consists of two parts treated as a single word.

No wāw between the parts (contrast: 21 = وَاحِد وَعِشرُون — wāw present → not compound)
All 11–19 (except 12) are mabniyyah (frozen): both parts carry fataḥ regardless of the number's iʿrāb position

The Frozen Rule

Position of number	Expected iʿrāb	Actual form
Fāʿil (marfūʿ)	ḍamma	أَحَدَ عَشَرَ (unchanged — fataḥ on both)
Mafʿūl (manṣūb)	fataḥ	أَحَدَ عَشَرَ (unchanged)
Majrūr	kasra	أَحَدَ عَشَرَ (unchanged — still fataḥ)

Exception: Number 12

12 is the only number in this range that declines. Its first part declines like a dual; the second part is frozen:

I'rab	Masculine	Feminine
Marfūʿ	اثنا عَشَرَ	اثنتا عَشَرَ
Manṣūb / Majrūr	اثنَي عَشَرَ	اثنَتَي عَشَرَ

Tamyīz for 11–19

The counted noun (tamyīz) is always singular and manṣūb:

إِنِّي رَأَيتُ أَحَدَ عَشَرَ كَوكَبًا — I saw eleven heavenly bodies. (Surah Yusuf 12:4) - أَحَدَ عَشَرَ = compound number (mabnī) - كَوكَبًا = tamyīz (singular, manṣūb with tanwīn fataḥ)

Tamyīz Note

The full explanation of tamyīz has been moved to Tamyiz.