the appropriate number of significant figures:

u. 6012.14 + 305.2

z.

18.9 X 21

--------------------------

--------------------------

v. 310.221 -- 6.1

aa.

0.269 - 3

--------------------------

--------------------------

w. 0.01154 + 0.23

ab. 662 - 18.0

--------------------------

--------------------------

x. 100.2 + 85

ac.

75 X 801

--------------------------

--------------------------

y. 66 -- 2

ad.

0.21 X 3.0233

--------------------------

--------------------------

The "common" logarithm (log) or the logarithm to the base ten (log10) of a

number is the exponent (power) to which the number ten must be raised to equal that

number. For example, the logarithm of 100 is equal to two, since the exponent (power)

to which the number ten (10) must be raised to equal 100 is two or 100 = 102. Since

logarithms are exponents, they follow the "Rules of Exponentiation" previously

discussed. The laboratory specialist can utilize logarithms to perform multiplication,

division, find roots, and raise a number to a power. A second use of logarithms is in the

solving of a number of equations used in the clinical laboratory; e.g., pH = -log [H+] and

absorbance = 2 - log %T

The work with logarithms in this subcourse will consist of traditional manual

methods with tables (see Appendix B) rather than the use of a calculator to

find logarithms and related values. Please remember this when you do the

exercises and the examination items. Logarithms are approximate values.

Comparable operations using a calculator will yield slightly different results in

most instances.

MD0837

1-29

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