Significance Formatter

Background: The number of significant figures (aka "sigfigs") in the value of a quantity reflects the accuracy with which it is known and/or the extent to which we care about its accuracy. Also, having fewer sigfigs enables more efficient use of real estate on a webpage. Roughly speaking, the number of sigfigs equals the number of nonzero digits. See Wikipedia for a more precise definition.
Instructions: Immediately after /significanceFormatter in the url, type /number/digits, where number is the particular quantity's value, and digits is the number of sigfigs with which you want this value expressed.
Example(s):
Input Outputs
sign number prefix
/-9987/3 - 9.99 k
/9987/2 (nothing) 10 k
/-99/3 - 99.0 (nothing)