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Compensatory Number

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Date: 01/29/2002 at 08:20:38
From: Kris Marshall
Subject: Math term: compensatory number

Is there a math definition for the term "Compensatory number"? In the
English dictionary compensation can mean an equivalent or balancing
but I'm not sure of the context.

She also wanted the definition of compatible number and I found
several references in the archives.

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Date: 01/29/2002 at 09:57:56
From: Doctor Sarah
Subject: Re: Math term: compensatory number

Hi Kris - thanks for writing to Dr. Math.

See:

Mathematics Glossary, Ohio Draft Education Standards
http://www.ohioctm.org/glos01.htm

Compensatory numbers are used to adjust numbers in a computation
after use of compatible numbers.

Example 1: 25 / 6 =~ (equals approximately) 24 / 6 = 4 is an
given as 4 + 1/6, where 1/6 is the compensatory number.

Example 2: 32 - 17 becomes 32 - 20 using compatible numbers. The
exact answer is 15, so the compensatory number allowing someone to
adjust the estimated difference is 3.

Example 3: 23 + 18  =~ 23 + 20 = 43. Since two was added to
increase 18 to 20 as compatible numbers, two will be subtracted
from 43 to compensate for the change. Thus, two is the compensatory
number.

Example 4: 32 - 17 = 35 - 20. This is the equal adding method
(three was added to both numbers in the subtraction problem), which
is not the same thing as compensatory numbers.

- Doctor Sarah, The Math Forum
http://mathforum.org/dr.math/
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Date: 01/29/2002 at 11:10:09
From: Kris Marshall
Subject: Math term: compensatory number

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