Numbers (sayılar) can function as adjectives when they quantify nouns.

Cardinal Numbers (Asal Sayılar):

These are the basic counting numbers. When used as adjectives, they precede the noun, and the noun remains in its singular form.

• bir (1), iki (2), üç (3), dört (4), beş (5), altı (6), yedi (7), sekiz (8), dokuz (9), on (10)
• on bir (11), yirmi (20), otuz (30), yüz (100), bin (1000)
• Example: iki elma (two apples - NOT iki elmalar)
• Example: beş kitap (five books)
• Example: yüz yirmi üç sayfa (one hundred twenty-three pages)

Ordinal Numbers (Sıra Sayıları):

Ordinal numbers indicate position or order (first, second, third, etc.). They are formed by adding a suffix to the cardinal number, following I-Type vowel harmony and consonant rules.

Suffixes:

• If cardinal ends in a consonant: -ıncı, -inci, -uncu, -üncü
  • Last vowel a, ı → -ıncı (altı → altıncı - sixth)
  • Last vowel e, i → -inci (beş → beşinci - fifth)
  • Last vowel o, u → -uncu (dokuz → dokuzuncu - ninth; on → onuncu - tenth)
  • Last vowel ö, ü → -üncü (üç → üçüncü - third; dört → dördüncü - fourth (t→d))
• If cardinal ends in a vowel: -ncı, -nci, -ncu, -ncü (effectively, the initial vowel of the full suffix is dropped)
  • iki → ikinci (second)
  • yedi → yedinci (seventh)

Note on 'bir' (one): "Birinci" (first) is the standard form.

Note on consonant softening: Some consonants at the end of numbers may soften before the suffix (e.g., dört → dördüncü).

Examples of Ordinal Numbers:

• birinci (1st), ikinci (2nd), üçüncü (3rd), dördüncü (4th), beşinci (5th), altıncı (6th), yedinci (7th), sekizinci (8th), dokuzuncu (9th), onuncu (10th)
• Example: birinci kat (first floor)
• Example: üçüncü sınıf (third grade/class)