Rounding LogicDate: 12/11/96 at 00:40:34 From: Mason Subject: Rounding Dr. Math, Who invented the fact that when you have 5,50,500,5000, etc. you always round UP, instead of down? Mason Date: 12/11/96 at 11:26:20 From: Doctor Rob Subject: Re: Rounding I haven't any idea why you round up, but there is a certain logic to it (although I'm not sure I agree with the results!). Consider numbers like 73.0, 73.1, 73.2, 73.3, 73.4, 73.5, 73.6, 73.7, 73.8, 73.9 just for the sake of this argument. Say we want to round them off to whole numbers. In an effort to be accurate, it is clear you should round down the first five and round up the last four. It is only the sixth number that leaves us in a bit of a pickle. It seems only fair/logical that if we round five cases down, we should round five cases up, too, rather than split the cases into six up and only four down. So maybe that's why it's the way that it is. It's also very important to have everyone who does math do the same thing so that their answers agree. We'd all be confused if some people rounded 550 up to 600 and others rounded it down to 500. That's a pretty big difference in results! Math is filled with lots of cases like this (they're called conventions) that you just have to follow so that we can talk to each other without being confused. -Doctor Rob, The Math Forum Check out our web site! http://mathforum.org/dr.math/ |
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