The term Number Pieces refers to a body of late compositions (40, or 41 if Seventeen was actually composed) by John Cage. Each piece is named after the number of performers involved: for instance, Seven is a piece for seven performers, One9 (read "One Nine") is the ninth work for one performer, and 1O1 is a piece for an orchestra of 101 musicians. The vast majority of these works were composed using Cage's time bracket technique: the score consists of short fragments (frequently just one note, with or without dynamics) and indications, in minutes and seconds, during which the fragment can start and by what time it should end. Time brackets can be fixed (e.g. from 1.15 to 2.00) or flexible (e.g. from anywhere between 1.15 and 1.45, and to anywhere between 2.00 and 2.30).
All of the Number Pieces were composed during the last six years of Cage's life, 1987–1992. Most are for traditional instruments, with six exceptions that range from works for rainsticks, the Japanese aerophone shō and conch shells to an electronically amplified version of 4′33″. This article lists all Number Pieces, organized by number of performers.
Inspired by the late “time bracket” compositions of John Cage, Brackets is intended primarily for instruments whose sounds and performance gestures are ill-served by traditional Western notation: “Bent” and homemade circuits; patchcord synthesizers; samplers; computer software; DJs setups; contact-miked objects; electric instruments with effect processors; pitch-indeterminate acoustic instruments, etc. A minimum of four musicians is needed, and there is no maximum size of the ensemble.
Each musician selects a number of distinct “gamuts” (between 4-9, the quantity determined by consensus of the group) that can be produced on her or his instrument. In the spirit of Cage’s Four6, these are different sounds “with fixed characteristics”. These gamuts could be determined by: the choice of a Bent circuit with a limited but identifiable sound signature (i.e., a Speak & Spell); the patching and settings of analog synthesizer modules; a prepared sample file; a software algorithm with specific parameter settings; the choice of object to be amplified with a contact mike; settings of an effect processor on an electric guitar; a specific percussion instrument.