Learn Arabic (Modern Standard): الأيام الثلاثة الأولى كانت صعبة.

For numbers 3 to 10, Arabic uses reverse agreement based on the noun's singular form. The singular of الأيام (days) is يوم, which is masculine. Therefore, the number takes the feminine marker ة, completely ignoring the non-human plural rule that applies to the rest of the sentence.

Usually we say ثلاثة أيام (three days). Why does the number come after the noun here as الأيام الثلاثة?

When a numbered phrase (3-10) becomes definite (meaning you add 'the'), the grammar changes. Instead of the typical number-first possessive structure, the noun comes first with ال (the), and the number follows it like a regular adjective, also taking ال.

English says 'the first three days'. Why is the word order الأيام الثلاثة الأولى in Arabic?

In Arabic, the core quantity (the cardinal number like الثلاثة) stays directly next to the noun it counts. Any other describing words, such as ordinals like الأولى (the first), must be placed after the number. Literally, the structure is 'the days, the three, the first'.

Why are الأولى, كانت, and صعبة all in the feminine singular form instead of plural?