Algebra
LOGARITHMS
LOGARITHMS
This chapter covers changing the base of a logarithm and solving problems with
logarithms.
EO 1.6
STATE the definition of a logarithm.
EO 1.7
CALCULATE the logarithm of a number.
Calculator Usage, Special Keys
This chapter will require the use of certain keys on a calculator to perform the necessary
calculations. An understanding of the functions of each key will make logarithms (logs) an easy
task.
Common Logarithm key
This key when pressed will compute the common log (base 10) of the
number x in the display, where x is greater than zero.
Natural Logarithm key
This key when pressed will compute the natural logarithm (base e) of the
number x in the display, where x is greater than zero.
This key when pressed before the log and ln keys will compute the anti-
log of the number x in the display. When used with the log key it will
raise 10 to the displayed power (107.12) and when used with the ln key will
raise (e) to the displayed power (e-381).
Introduction
Logarithms are exponents, as will be explained in the following sections. Before the advent of
calculators, logarithms had great use in multiplying and dividing numbers with many digits since
adding exponents was less work than multiplying numbers. Now they are important in nuclear
work because many laws governing physical behavior are in exponential form. Examples are
radioactive decay, gamma absorption, and reactor power changes on a stable period.
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