Expert: Abe Mantell - 1/16/2005

Question
Why do you round up when you have something like 0.55 (e.g., to 0.6 for one decimal place)? Surely the number 5 is not more than half, so should you not keep the number at 0.55 rather than rounding up for one decimal place or one significant figure?  

Answer
Good question!

As far as I know, the "rule" to round-up when the digit
is exactly "5" is somewhat arbitrary.  In fact, what
should be done, when doing lots of rounding, is to
try and balance the "rounding-up" and "rounding-down"
so in the long-run there is not too much of an
over-estimate or under-estimate...and hopefully, the
overall rounding process is balanced enough to yield
a good result.