Ordinal numbers: the period and adjective endings
Ordinal numbers are words like "first", "second", and "third" that tell us the position of something in a list. In German, reading and writing ordinals can be a stumbling block for learners. This is because they use a simple punctuation mark in writing, but require specific adjective endings when spoken aloud.
Whether you are talking about floors in a building, items in a sequence, or dates on a calendar, German ordinals adapt to fit the grammar of the sentence.
In English, we write ordinals with endings like "st", "nd", or "th" (1st, 2nd, 4th). In German, you simply place a period right after the number: 1., 2., 4. This period tells you that the number is an ordinal.
When spoken, ordinals act exactly like adjectives. For numbers from two to nineteen, you add a -t- to the number, followed by an adjective ending. For numbers twenty and above, you add -st- plus the ending. If you are describing a standard subject with a definite article like der, die, or das, the ending is usually just -e.
A few common numbers have irregular ordinal forms, which you will need to memorize. The word for "first" is erste. The word for "third" changes its vowel to become dritte. The number seven drops its final letters to become siebte. Finally, because the number eight already ends in a "t", it simply shares that letter to become achte.
Ordinals are most frequently used for dates. In German, you usually state a date using the word am (a combination of an and dem). Because ordinals follow adjective rules, this grammatical case changes the adjective ending from -e to -en.
When you read a written date like "am 30. Mai", you must remember to supply this ending yourself. It is pronounced am dreißigsten Mai.
In writing, German ordinals are marked with a period. In speech, they act like adjectives: add -t- (up to 19) or -st- (20 and up) plus the correct adjective ending, remembering that dates with am require an -en ending.