(div! place ..args)
  place: a place
  args: zero or more forms

Performs in-place division or reciprocation.

(div! x 9 10) is equivalent to (= x (/ x 9 10)), except that x is only evaluated once.

This means that with only one argument, (div! x) replaces x with its reciprocal, (/ 1.0 x).

See also: /