Arabic has certain rules to deal with numbers. These are based on the number itself, and also the gender of the subject.
Here are the numbers from 1 to 10 in Arabic. The numbers are are in words next to the symbol for each:
Rules for numbers 1 and 2
The numbers 1 and 2 always match the gender of the noun they qualify. That is, their form is masculine with masculine nouns and feminine with feminine nouns. These are اِثْنَان/ وَاحِد with masculine nouns and وَاحِدَة / اِثْنَتَان with feminine nouns, as in these examples:
يومٌ وَاحِدٌ | one day
ُحُجرَةٌ وَاحِدَةٌ | one room
جَاءَ عَالمِانِ اِثْنَان | Two scientists came
قَرَأتُ رِسَالَتَينِ اِثْنَتَين | I read two letters
Remember: The numbers 1 and 2 in Arabic follow the noun they modify and agree with it in case and gender.
Rules for numbers 3-9
For numbers 3-9, we use plural nouns, disagreeing with the gender of the noun, Nouns that follow these numbers should be indefinite genitive plural, as in these examples:
Keep in mind that the numbers 3-10 are made masculine by just dropping ‘ta’, the feminine marker from the end. (ة )
سَبْعَةُ كُتُبٍ| seven books
تِسْعُ سَيَّارَاتٍ | nine cars
Just remember, the number has the opposite gender of the singular noun.