title: Is NSDecimalNumber really necessary to do some quite simple tasks?
body: <p>It started quite normally. I'm writing complex calculation application for iPhone. I decided to use float primitive for representing numbers. So, time came to start rounding and formatting output, but first of all rounding. I want to round numbers to different number of decimal places. FOund out there is no useful C function. OK, so I can write my own. But then I have numbers from application settings to persist. 
  I found out only objects can be persisted.
  So I started to dig in NSNumber and NSDecimalNumber. Especially the latter gives me shivers only when look at it. Delegate needed to implement roundings, no smiple arithmetic operators, special methods instead....:(
  What is left then of pure C simplicity?</p>
  
  <p>Is there any other way to simplify this?</p>