Month + Number + 日
The measure word 日 (rì) is used to express specific days of the month in Chinese. It is placed after a number to indicate a calendar date, as in 三十一日 (the 31st). It is more formal than 号, which is used in spoken Chinese for the same purpose.
会议定在十月十五日下午两点举行。
huìyì dìng zài shí yuè shí wǔ rì xiàwǔ liǎng diǎn jǔxíng.
The meeting is scheduled for 2:00 PM on October 15th.
他的生日是三月八日。
tā de shēngrì shì sān yuè bā rì.
His birthday is March 8th.
报名截止日期为七月三十一日。
bàomíng jiézhǐ rìqī wéi qī yuè sānshí yī rì.
The registration deadline is July 31st.