Learn Turkish: Asansör dördüncü katta durdu. - The elevator stopped on the fourth floor.

To make ordinal numbers (like first, second, third), Turkish adds the suffix -inci, -uncu, -ıncı, or -üncü depending on vowel harmony. For dört, we use the -üncü suffix.

Why does the 't' in dört change to a 'd' in dördüncü?

This happens because of consonant mutation. When a Turkish word ends in a hard consonant like 't' and you add a suffix starting with a vowel (like -üncü), that hard consonant often softens. Here, 't' becomes 'd' to make pronunciation smoother.

The suffix for "in" or "on" is usually -da or -de. Why is it -ta in katta?

This is due to consonant assimilation, sometimes taught as the "Fıstıkçı Şahap" rule. If a word ends in a voiceless, hard consonant (like the 't' in kat, which means floor), the suffix must also start with a voiceless consonant. So, the -da suffix hardens to -ta.

Why does durdu end in -du instead of -di for the past tense?