Fractions

Level 5

Fractions in Arabic are treated as nouns, not adjectives. They typically follow the فُعُل (fuʿul) pattern for 1/3 through 1/10, while 1/2 has a unique form نِصْف (niṣf).

How It Works

Arabic fractions are highly systematic. Here is how they are structured:

  • Basic Fractions (1/2 - 1/10): 1/2 is نِصْف. For 1/3 to 1/10, the pattern is فُعُل or فُعْل. For example, 1/3 is ثُلُث and 1/4 is رُبُع.
  • Plural Forms: Fractions use the broken plural pattern أَفْعَال. For example, أَثْلَاث for thirds and أَرْبَاع for quarters.
  • Compound Fractions (e.g., 3/5): These follow the rules of gender polarity. Since all fraction nouns are masculine, the number (3-10) must be feminine. The numerator is the head of the idafa and declines for case, while the denominator remains in the genitive plural. Example: ثَلَاثَةُ أَخْمَاسٍ (three fifths).
  • Dual Fractions (e.g., 2/3): Use the dual ending. The nominative ending ـانِ changes to ـَيْنِ in the accusative and genitive cases. Note that the ن is dropped in an idafa when followed by a noun: ثُلُثَا الكِتَابِ (two-thirds of the book).
  • Mathematical Fractions (X over Y): In modern contexts like science or news, fractions are often expressed using the preposition على (on/over). For example, 3/4 is ثَلَاثَة عَلَى أَرْبَعَة (three over four).
  • Fractions 1/11 and Above: For denominators 11 and higher, use the phrase جُزْء مِن followed by the cardinal number. For example, 1/15 is جُزْءٌ مِن خَمْسَةَ عَشَرَ.

Names and Mixed Numbers: A fraction is كَسْر, plural كُسُور. Join a whole amount to the fractional remainder with و: وَاحِدٌ وَنِصْفٌ (one and a half), اِثْنَانِ وَرُبُعٌ (two and a quarter). With a unit, natural phrasing is سَاعَةٌ وَنِصْفٌ (an hour and a half), or اِنتظرتُ ساعتينِ ورُبعًا (I waited two and a quarter hours). The case follows the sentence function.

The numerator-over-denominator reading also works beyond ten: وَاحِدٌ عَلَى خَمْسَةَ عَشَرَ is 1/15. In a fully explicit “one part out of” expression, say جُزْءٌ مِنْ خَمْسَةَ عَشَرَ جُزْءًا. The denominator is not required to have a special lexical fraction name.

Examples (6)

  1. انْتَظَرْتُكَ نِصْفَ سَاعَةٍ.

    I waited for you for half an hour.

    Word by Word: I-waited-for-you half (of) hour.

    Here, 'nisf' (half) is the first part of an idafa, putting 'sa'atin' in the genitive case.

  2. قَرَأْتُ ثُلُثَيِ الكِتَابِ.

    I read two-thirds of the book.

    Word by Word: I-read two-thirds (of) the-book.

    The dual form 'thuluthayn' becomes 'thuluthayi' because the 'nun' is dropped in an idafa construction.

  3. يَمْلِكُ ثَلَاثَةَ أَخْمَاسِ الشَّرِكَةِ.

    He owns three-fifths of the company.

    Word by Word: He-owns three fifths (of) the-company.

    Note the feminine number 'thalathata' used with the masculine plural 'akhmas'.

  4. أَكَلَ الطِّفْلُ رُبُعَ التُّفَّاحَةِ.

    The child ate a quarter of the apple.

    Word by Word: Ate the-child quarter (of) the-apple.

    The fraction 'rubuʿ' (1/4) acts as a noun governing the following word.

  5. النَّتِيجَةُ هِيَ ثَلَاثَةٌ عَلَى أَرْبَعَةٍ.

    The result is three over four (three-quarters).

    Word by Word: The-result she three on four.

    In modern mathematical contexts, the preposition 'ala' (on/over) is used to express fractions.

  6. اِنْتَظَرْتُ سَاعَةً وَنِصْفًا.

    I waited an hour and a half.

    Word by Word: I waited an hour and a half.

    و joins the whole unit to the remaining fraction; both ساعةً and نصفًا are accusative in this duration expression.

Common Mistakes

  • Using masculine numbers for compound fractions.

    ثَلَاث أَرْبَاع
    ثَلَاثَة أَرْبَاع

    Because the singular fraction (rubuʿ) is masculine, the number 3-10 must be feminine (thalathah) according to the rules of gender polarity.

  • Confusing fractions with ordinal numbers.

    الجُزْء الثُّلُث
    الجُزْء الثَّالِث

    Thuluth means 'one-third' (a noun), while thalith means 'third' (an adjective). Use the fa'il pattern for ordinals.

How It Connects

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FractionsLevel 5

Learn This First

To understand Arabic fractions, you need to be familiar with the root and pattern system, as fractions like 'rubu' (quarter) or 'thulth' (third) are formed using fixed morphological templates derived from the roots of the numbers 3 through 10.