Why is “number” abbreviated as “No.”? [duplicate]

The spelling of number is number, but the abbreviation is No (№). There is no letter o in number, so where does this spelling come from?

No (frequently stylized №) is the abbreviation for Latin: numero (in number). It’s used even though the word being abbreviated is English: number. Other examples of this practice:

• lb, abbreviation of Latin: libra (balance) – used as abbrevation for English: pound

• &, a stylized way to write Latin: et (and) – used as abbreviation for English: and

Why? These Latinate abbreviations were second nature to educated people who wrote in Latin. When they wrote in English, they carried these abbreviations over to the “new” language.