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ESTIMATION TECHNIQUES  
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ESTIMATION TECHNIQUES

One of the most important things to remember when using a slide rule is that it does not keep track of the position of the decimal point.  As far as it's concerned numbers like 0.00675, 0.0675, 0.675, 6.75, 67.5, 675, 6750 and 67500 are all the same.  So it will do the calculation and give you the digits, but you need to be able to determine the position of the decimal point in the answer.

Over the years, a number of methods for helping users position the decimal point have been devised; some are very complicated and others are a little easier to handle.  We shall look at a few different ways of performing this important task.

 

 

 

 

 
 

DIGIT COUNTING
Over the centuries, a number of different methods have been devise to keep track of the decimal point in calculations using the slide rule.  These consisted of:

  • inspection
  • approximation
  • digit counting
  • scientific notation; and
  • instructional aids

just to name a few.

Here, we will look at one method of digit counting which I think is quite simple to use.  The disadvantage is that these methods seemed to be binary, in that they only applied to two values at a time.