Comments on: Maths worksheet: Rounding to the nearest 10 http://mathsblog.co.uk/2009/03/14/maths-worksheet-rounding-to-the-nearest-10/ Maths help for parents of children aged 5 to 11 Sun, 05 Sep 2010 16:24:08 +0000 hourly 1 http://wordpress.org/?v=3.0 By: Peter http://mathsblog.co.uk/2009/03/14/maths-worksheet-rounding-to-the-nearest-10/comment-page-1/#comment-1147 Peter Thu, 26 Mar 2009 14:09:23 +0000 http://mathsblog.co.uk/?p=2136#comment-1147 Hello Keith Thanks for the email. You spotted the (not quite deliberate) mistake which I have now rectified. I take your point about bias, especially in a long list of values. One of the main aims of rounding at this age is so that children can do quick mental calculations to check that their written answers or use of a calculator are sensible. They will quickly go on to round to the nearest 100 or 1000. Thanks Peter Hello Keith
Thanks for the email. You spotted the (not quite deliberate) mistake which I have now rectified. I take your point about bias, especially in a long list of values. One of the main aims of rounding at this age is so that children can do quick mental calculations to check that their written answers or use of a calculator are sensible. They will quickly go on to round to the nearest 100 or 1000.
Thanks
Peter

]]> By: Keith Imrie http://mathsblog.co.uk/2009/03/14/maths-worksheet-rounding-to-the-nearest-10/comment-page-1/#comment-1144 Keith Imrie Wed, 25 Mar 2009 22:05:33 +0000 http://mathsblog.co.uk/?p=2136#comment-1144 If you always round up (or down) when the number ends in 5, you get a bias in a table of values. (So the total is biased high (or low), for example.) Better is to round to the nearest multiple of 20. You say "If the units are 5 or more, round up to the next whole ten." and "55 to the nearest whole ten is 50" But these do not agree. If you always round up (or down) when the number ends in 5, you get a bias in a table of values. (So the total is biased high (or low), for example.) Better is to round to the nearest multiple of 20.

You say
“If the units are 5 or more, round up to the next whole ten.”
and
“55 to the nearest whole ten is 50″

But these do not agree.

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