In order to change a singular Arabic noun to the Dual the following steps are involved:

Nominative Case:

• To change a singular masculine noun to the the case of dual the following changes occur:

  1. The last letter of the word has its vowel replaced with a single fatha (i.e. replacing the damma or dammatain)

  2. The suffix of  انِ is added to the word.

  See some examples below:

  طَالبٌ will become طَالِبَانِ  and

  الْطَّالِبُ will become الْطَّالِبَانِ 

• To change a singular feminine noun with nominative case to the Dual, the following changes occur:

1. The last letter ةُ ta marboota is changed to the letter ت  

2. The last letter (which is now ت ) has its vowel replaced with a single fatha  (i.e. replacing the damma or dammatain),

3. The suffix of  انِ is added to the word.

See some examples below:

•  طَالبَةٌ will become طَالِبَتَانِ  and

• الْطَّالِبَةُ will become الْطَّالِبَتَانِ 

Genitive and Accusative Case:

• To change a singular masculine noun with accusative or genitive case to the Dual:

1. A single fatha is added on the last letter instead of the accusative case (with a fatha) or genitive case (with a kasra)

2. The suffix Ya-Nun يْنِ i.e., a Ya with Sukoon and Nun with a Kasra is added.

   See some examples below:

   مَعَ مُدَرِّسٍ will become مَعَ مُدَرِّسَيْنِ and

   عِنْدَ الْمُدَرِّسِ will become عِنْدَ الْمُدَرِّسَيْنِ

   To change a singular feminine noun with accusative or genitive case to the Dual:

• فِي حَقِيْبَةٍ will become فِي حَقِيْبَتَيْنِ and

• فَوْقَ الْشَّجَرَةِ will become فَوْقَ الْشَّجَرَتَيْنِ