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Unformatted text preview: decimal place. A related difficulty is whether crude truncation or correct rounding
is sought. Again, it is up to the teacher. Probably the single most important idea concerning calculators
that all pupils should leave school with, is that there is nothing intrinsically “more accurate” in writing
down every figure in a calculator display. Together with the continual thought that, just because a number
appears on a calculator display it does not mean that it is necessarily correct!
Third is when, in solving more complex problems, it is necessary to work in stages, using the
information gained in one stage to work out something in the next stage, and so on. This notion is not
difficult to grasp. What is a little more difficult to understand and handle, is the idea of “cumulative
error”. Even if no mistake is made, we do introduce an error when we truncate the reading on the
calculator, especially if correct rounding is not being used. This error is then carried forward and used in
the next stage. The only (relatively) safe and reasonable way of dealing with this is to say that, whatever
degree of accuracy we might require in our final answer, then we should carry forward at least 2 more
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This document was uploaded on 03/01/2014.
- Spring '14