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Algorithms, long division in particular
Posted:
Feb 23, 1995 7:01 PM


I am going to defend the teaching of the long division algorithm I learned (which I egocentrically assume is the long division algorithm everyone else is talking about) in the early grades.
On page 47, in the grades 14 section, the standards document says:
"It is important for children to learn the sequence of steps  and the reasons for them  in the paperandpencil algorithms used widely in our culture. Thus, instruction should emphasize the meaningful development of these procedures, not speed of processing. . . problems with remainders should be integrated throughout division. This approach is more efficient and eliminates some misconceptions that often occur."
At the end of the next paragraph, the standards document continues,
"Although the exploration of computation with larger numbers is appropriate, excessive amounts of time should not be devoted to proficiency."
It is clear the the standards document advocates teaching a (the) division algorithm, but _repeated_ exercises on the order of 142748 divided by 372 is wasteful. I wholeheartedly agree.
Now for my personal spin on algorithms. Humans have spent countless effort to develop efficient means for accomplishing all sorts of tasks. In mathematics, we see dozens or thousands of algorithms put to use, depending on our level of immersion and experience. The long division algorithm and the multiple digit multiplication algorithm (again, the one I use based on the distributive law) are the earliest instances I recall of iterated algorithms with multiple _different_ operations; division is the first with a nontrivial ending condition.
Throughout subsequent mathematics we encounter such algorithms of all types. Sometimes, in "real life," for physical, temporal, or economic reasons, it is necessary to use algorithms for single or repeated operations. We do need to teach our students how to apply algorithms. I happen to prefer long division because if we have to wait for factoring or Euclid's algorthm or Horner's algorithm or L'Hopital's rule, we're dead before we start.
Ed
 Edward S. Miller edmiller@lcsc.edu
Division of Natural Sciences VOICE 2087992810 LewisClark State College FAX 2087992064 500 8th Avenue Lewiston ID 835012698 USA 



