number (v.) Look up number at
c. 1300, "to count," from Old French nombrer "to count, reckon," from nombre (n.) "number" (see number (n.)). Meaning "to assign a number to" is late 14c.; that of "to ascertain the number of" is from early 15c. Related: Numbered; numbering.
number (n.) Look up number at
c. 1300, "sum, aggregate of a collection," from Anglo-French noumbre, Old French nombre and directly from Latin numerus "a number, quantity," from PIE root *nem- "assign, allot; take." Meaning "symbol or figure of arithmetic value" is from late 14c. Meaning "single (numbered) issue of a magazine" is from 1795. Meaning "dialing combination to reach a particular telephone receiver" is from 1879; hence wrong number (1886). The modern meaning "musical selection" (1885) is from vaudeville theater programs, where acts were marked by a number. Earlier numbers meant "Harmony; proportion calculated by number," and "Verses, poetry" [Johnson].

Number one "oneself" is from 1704 (mock-Italian form numero uno attested from 1973); the biblical Book of Numbers (c. 1400, Latin Numeri, Greek Arithmoi) so called because it begins with a census of the Israelites. Slang number one and number two for "urination" and "defecation" attested from 1902. Number cruncher is 1966, of machines; 1971, of persons. To get or have (someone's) number "have someone figured out" is attested from 1853. The numbers "illegal lottery" is from 1897, American English.