Chemistry Reference
In-Depth Information
before
the division indicated by the fraction bar. For example, to simplify the
expression
a
b
c
d
the difference is divided by the sum The addition and sub-
traction, despite being lower in precedence, are done before the division. In the
other forms of representation, this expression is written as
(
a
b
)
(
c
d
).
(
a
b
)
(
c
d
)
or
(
a
b
)
(
c
d
)
where the parentheses are required to signify that the addition and subtraction
are to be done first. A calculator usually has only one operation key for divi-
sion, When using the calculator, be careful to indicate what is divided by
what when more than two variables are involved.
.
The Change Sign Key
If we want to enter a negative number, the number is entered first, and then its
sign is changed with the change sign key,
not
the subtraction key.
Exponential Numbers
When displaying a number in exponential notation, some calculators show the
coefficient followed by a space or a minus sign and then two digits giving the
value of the exponent. For example, the following calculator displays represent
and
10
4
10
4
,
1.23
1.23
respectively:
1.23
04
1.23
04
Coefficient
Exponent
Note that the base (10) is not shown explicitly on these calculators. On other
calculators, where it is shown, interpreting the values of numbers in exponen-
tial notation is slightly easier.
To enter a number in exponential form, use the special key, or ,
meaning “ to the power,”
not
the multiplication key. To enter a negative
number, press the change sign key before
EE
EXP
10
EE
or
EXP
; to enter a negative expo-
nent, press the change sign key after or .
Some calculators display answers in decimal notation unless they are pro-
grammed to display them in scientific notation. If a number is too large or too
small to fit on the display in decimal format, the calculator will use scientific
notation automatically. To get a display in scientific notation for a reasonably
sized decimal number, see the owner's manual. If an easy conversion is not
available, multiply the decimal value by (if the number is greater
than 1) or (if the number is less than 1), and mentally subtract or
add 10 to the resulting exponent.
EE
EXP
Learn how to convert a number
in exponential notation to
decimal format and vice versa.
10
10
1
10
10
1
