In my chemistry and biochemistry courses I make extensive use of formula quiz questions. It would often be nice to be able to specify the increment between values of variables that are used. For example, if one of my variables is "x", it would be nice to specify that x ranges from 10 to 80 in increments of 10. I would imagine that this would be useful for other science and math disciplines as well.
In addition, it would be extremely helpful to be able to specify the number of significant digits to display for each variable. If three significant digits were selected, and x ranged from 10 to 200 in steps of 0.1, then 45.3 would be displayed but 105.2 would not (it would be rounded to 105). This type of capability would enhance our ability to teach and test on the rules for significant digits.