The correct spelling for the word "doest number" is actually "dost number". The IPA phonetic transcription for "dost" is /dʌst/. It is a Middle English verb form that means "does". In modern English, this form is no longer used except in some formal or archaic contexts. The word "number" is spelled as it is in modern English and has the IPA transcription of /ˈnʌmbər/. Together, "dost number" means "does number" in modern English.
The phrase "doest number" does not have a separate etymology because it is a combination of two words: "doest" and "number".
The word "doest" is the archaic second person singular present form of the verb "do" in English. In Middle English, "doest" was used to address a single person. However, this form is no longer in common use in modern English, where "do" is used instead.
The word "number" comes from the Old French word "nombre", from the Latin word "numerum", meaning "a sum, total, or number". It has been used in English since the 14th century.
Therefore, "doest number" can be understood as a combination of the archaic form of "do" plus the word "number". However, it's important to note that this combination is not commonly used in modern English.