There was a discussion about how whether or not kids should be taught how to write cursive here a little while ago in the comments, and I thought that Kain’s hippie prescriptions for public education — which I strongly agree with — provided a good opportunity to bring up something that I oppose even more than I oppose the teaching of cursive: the teaching of long division. Long division is an utter and complete waste of time, I doubt that more than 2% of adults can still do it, and, moreover, why would you ever do it in a world where there are calculators?
The worst part about long division is that it elbows out a much more important topic, order of magnitude estimation. The ability to estimate orders of magnitude is very valuable and division is a good place to do it. Rather than having kids divide 135 into 5000 with a long-winded mechanical method, why not teach them to estimate that, first off, the answer will be between 10 and 100 (just by counting digits) and then push it down to saying it’s somewhere between 20 and 50 (since 135 is between 100 and 200).
Megan McArdle’s errors along these lines are particularly egregious but not atypical. I wonder what percentage of Americans know how many millions are in a billion and how many billions are in a trillion. Without a feeling for this, it’s almost impossible to understand even the crudest macro-economic arguments.