This is documentation for Mathematica 6, which was
based on an earlier version of the Wolfram Language.
View current documentation (Version 11.2)

Slot (#)

represents the first argument supplied to a pure function.
represents the n^(th) argument.
  • # is used to represent arguments or formal parameters in pure functions of the form body& or Function[body].
  • # is equivalent to Slot[1].
  • #n is equivalent to Slot[n]. n must be a non-negative integer.
  • #0 gives the head of the function, i.e., the pure function itself.
New in 1