HP HP-25 User guide
HEWLETT-PACKARD
“The
success
and
prosperity
of
our
company
will
be
assured
only
if
we
offer
our
customers
superior
products
that
fill
real
needs
and
provide
lasting
value,
and
that
are
supported
by
a
wide
variety
of
useful
services,
both
before
and
after
sale.”
Statement
of
Corporate
Objectives.
Hewlett-Packard
When
Messrs.
Hewlett
and
Packard
founded
our
company
in
1939,
we
offered
one
superior
product,
an
audio
oscillator.
Today,
we
offer
more
than
3,000
quality
products,
designed
and
built
for
some
oT
tne
wWorla
s
Most
discerning
customers.
Since
we
introduced
our
first
pocket
calculator
in
1972,
we've
sold
over
700,000
world-wide.
Their
owners
include
Nobel
laureates,
astronauts,
mountain
climbers,
businessmen,
doctors,
students,
and
housewives.
Each
of
our
pocket
calculators
is
precision
crafted
and
designed
to
solve
the
problems
its
owner
can expect
to
encounter
through-
out
a
working
lifetime.
HP
calculators
fill
real
needs.
And
they
provide
lasting
value.
(Cover
background
courtesy
of
NASA)
HEWLETT
|zfi|
PACKARD
HP-25
Owner’s
Handbook
August
1975
00025-90001
Rev.
C
8/75
Printed
in
U.S.A.
©Hewlett-Packard
Company
1975
Contents
The
HP-25
Programmable
Scientific
Calculator
......
...
...
..
...
..
...
...
5
Function
Key
Index
...........
. .
i,
5
HP-25
Memory
......
...
6
Programming
Key
Index
...........................
...
6
The
HP-25
Means
Painless
Programming
..............
9
Manual
Problem
Solving
.............
...
...
9
Programmed
Problem
Solving
.........................
10
Section
1:
Getting
Started
.............................
13
Display
.
...
..o
13
Keyboard
...
...
13
Keying
In
Numbers
........
...
.
...
...
.
.
14
Negative
Numbers
......
... ...
...
...
14
Clearing
..o
oo
15
Functions
...
15
Chain
Calculations
...........
...
...
...
i
18
A
Word
Aboutthe
HP-25.
..
............................
22
Section
2:
Controlling
the
Display
......................
25
Display
Control
Keys
...
i
25
Automatic
Display
Switching...........................
30
Keying
In
Exponents
of
Ten
...........................
31
Calculator
Overflow
.........
...
...
.
.
.
33
Error
Display
...
33
Section
3:
The
Automatic
Memory
Stack
............
..
35
The
Stack
.
...
35
Initial
Display
..
..ot
35
Manipulating
Stack
Contents
..........................
35
Clearing
the
Stack
...............
.. oo
it
37
The
KBY
oo
38
One-Number
Functions
and
the
Stack
..................
40
Two-Number
Functions
and
the
Stack
..................
40
Chain
Arithmetic
........
...
.
42
Order
of
Execution
.........
...
.
..
45
Constant
Arithmetic
.............
...
.
...
...
46
Section
4:
Function
Keys
...............................
49
LAST
X
49
Prefix
Clear
.......
...
50
Number
Alteration
Keys
..............................
51
Reciprocals
...
52
Square
ROOS
.
..o
52
SQUANING
«
o
53
Using
Pi
..o
53
Percentages
...t
54
Storage
Registers
...............
..
55
Trigonometric
Functions
.............................
59
Polar/Rectangular
Coordinate
Conversion
.............
62
Logarithmic
and
Exponential
Functions
...............
63
Statistical
Functions
...............
...
...
66
Vector
Summations
.........
...
i
70
Section
5:
Programming
...............................
73
What
Isa
Program?
.........
...
... ..
...
73
Why
Write
Programs?
...............
..
...
...
..
...
73
Three
Modes
of
Operation
..........
.. .. ..
...
... ...
74
Introductory
Program
................
.
...
75
Running
a
Program
...................
...
..
...
...
78
GTO
00
..o
78
Writing
a
Second
Program
...........................
79
Interrupting
Program
Execution.......................
82
Branching
...........
..
...
..
...
87
Editing
a
Program
..........
...
...
... ... ...
...
91
Program
Applications
...................
..
...
...
...
97
Afterword
...
99
Appendix
A:
Accessories,
Service,
and
Maintenance
101
Standard
Accessories
..................
i
101
Optional
Accessories
......................ciiii
..
101
AC
Line
Operation
...................................
101
Battery
Charging
.....................................
102
Battery
Operation
............
.
...
.
...
.
...
.
...
...
103
Battery
Pack
Replacement
............................
104
Service
...
105
Temperature
Range
...............
... ...
.
............
106
Warranty
...
106
Appendix
B:
Improper
Operations
...............
..
...
109
Appendix
C:
Stack
Lift
and
LAST
X
...........
...
.
111
Function
Key
Index
Manual
RUN
Mode.
PRGM-RUN
switch
erov
T
Av
set
to
RUN.
Function
keys
pressed
from
the
keyboard
execute
individual
functions
as
they
are
pressed.
Input
numbers
and
answers
are
displayed.
[F1X]Fixed
display.
Followed
by
a
number
key,
selects
fixed
point
notation
display
(page
26).
Scientific
display.
Followed
by a
number
key,
selects
scientific
notation
display
(page
27).
Engineering
display.
Followed
by
a
number
key,
selects
engineering
notation
display
(page
28).
n
Prefix
key.
Press
before
function
key
to
select
function
printed
in
gold
on
the
keyboard
above
function
key
(page
13).
BPrefix
key.
Press
before
function
key
to
select
function
printed
in
blue
on
slanted
face
of
function
key
(page
13).
Mean.
Calculates
mean
(average)
of
the
numbers
totaled
by
in
storage
register
R;
(page
67).
x
exchange
y.
Exchanges
contents
of
X-
and
Y-registers
(page
37).
E]Standard
deviation.
Calculates
standard
deviation
using
numbers
totaled
by
in
storage
registers
R,
through
m
Roll
down.
Rolls
down
contents
of
stack
for
viewing
in
displayed
X-register
Reciprocal.
Calculates
reciprocal
of
the
number
in
the
display
(page
52).
Store.
Followed
by
number
key,
stores
displayed
number
in
storage
register
(0-7)
specified.
Followed
by
arithmetic
operator
key,
performs
storage
register
arithmetic
[=8Recall.
Followed
by
number
key,
recalls
value
from
storage
register
(0-7)
specified
into
the
displayed
X-register
(page
55).
[%]
Percent.
Calculates
Summation
x%
of y
(page
54).
minus.
Subtracts
values
from
storage
registers
R;
through
R,
for
correcting
summation
entries
(page
69).
Summation.
Sums
numbers
in
X-
and
Y-registers
into
storage
registers
R;
through
R,
(page
66).
Clear
prefix.
Atter
[
.
[
B3
-
or
,
cancels
that
key
(page
50).
IS\
lEY
Copies
number
in
displayed
X-register
into
Y-register
(page
16).
Change
sign.
Changes
sign
of
displayed
number
or
exponent
of
10
(page
14).
[cEG]Degrees.
Sets
decimal
degree
mode
for
trigonometric
functions
(page
59).
[FC]Clear
registers.
Replaces
contents
of
storage
registers
R,
through
R,
with
zeros
(page
56).
@Enter
exponent.
After
pressing,
next
numbers
keyed
in
are
exponents
of
10
(page
31).
Radians.
Sets
radians
mode
for
trigonometric
functions
(page
59).
Clear
stack.
Replaces
contents
of
X-, Y-,
Z-,
and
T-
registers
with
zeros
(page
37).
Clear
x.
Clears
the
displayed
X-
register
to
zero
(page
15).
[GRD]
Grads.
Sets
grads
mode
for
trigonometric
functions
(page
59).
(-]
[=]
Arithmetic
operators
(page
16).
[E]
Natural
logarithm.
Computes
natural
logarithm
(base
e,
2.718.
.
.)
of
value
in
displayed
X-register
(page
63).
Natural
antilog.
Raises
e
(2.718.
.
)
to
the
power
of
value
in
displayed
X-register
(page
63).
Common
logarithm.
Computes
common
logarithm
(base
10)
of
value
in
displayed
X-register
(page
63).
Common
antilogarithm.
Raises
10
to
the
power
of
number
in
displayed
X-register
(page
63).
Rectangular
coordinate
conversion.
Converts
polar
magnitude
and
angle
in
X-
and
Y-
registers
to
rectangular
x
and
y
coordinates
(page
62).
Polar
coordinate
conversion.
Converts
X,
y
rectangular
coordinates
placed
in
X-
and
Y-registers
to
polar
magnitude
and
angle
(page
62).
[sin]
Sine,
cosine,
and
tangent.
Calculate
the
sine,
cosine, or
tangent
of
value
in
displayed
X-register
(page
59).
Arc
sine,
arc
cosine,
arc
tangent.
Calculate
inverse
trigonometric
function
of
value
in
display
(page
59).
["TJinteger.
Leaves
only
integer
portion
of
number
in
displayed
X-register
by
truncating
fractional
portion
(page
51).
Fraction.
Leaves
only
fractional
portion
of
number
in
displayed
X-register
by
truncating
integer
portion
(page
51).
Computes
square
root of
number
in
displayed
X-register
(page
52).
[
Jcomputes
square
of
numberindisplayed
X-register
(page
53).
Raises
number
in
Y-register
to
the
power
of
the
number
in
the
displayed
X-register
(page
64).
Absolute.
Gives
the
absolute
value
of
the
displayed
number
(page
51).
Converts
displayed
decimal
hours
or
degrees
to
hours,
minutes,
seconds
format
(page
60).
@
Converts
displayed
value
in
hours,
minutes,
seconds
format
to
decimal
hours
or
degrees
(page
60).
Recalls
number
displayed
before
the
previous
operation
back
into
the
displayed
X-register
(page
49).
Pi.
Places
value
of
pi
(3.14159.
.
)
into
displayed
X-
register
(page
53).
HP-25
Memory
Automatic
Memory
Stack
Qe
|
IR
Exponent
of
10
sign
Exponent
of
10
v
—_—
Sign
Mantissa
Storage
Registers
SCI
@
=
-
R
[T
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T
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PRGM
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X<y
In
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R
R5
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R
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Y
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sin
cos
tan
R7
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Y
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X#y
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x
¥
Program
Memory
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Automatic
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Stop
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Programming
Key
Index
PROGRAM
Mode
PRGM-RUN
switch
set
to
:
prom
[T
run
Function
keys
are
recorded
in
program
memory.
Display
shows
program
memory
step
number
and
the
keycode
(keyboard
row
and
location
in
row)
of
the
function
key.
Active
keys:
In
program
mode
only
three
keys
are
active.
These
keys
cannot
be
recorded
in
program
memory.
Clear
program.
Clears
program
memory
to
GTO
00
instructions
and
resets
calculator
so
operations
begin
at
step
00
of
program
memory
(page
78).
Automatic
RUN
Mode
PRGM-RUN
switch
set
to:
rem
[T
~un
Function
keys
may
be
executed
as
part
of a
recorded
program
or
individually
by
pressing
from
the
keyboard.
Input
numbers
and
answers
are
displayed,
except
where
indicated.
Pressed
from
keyboard:
Resets
calculator
so
operations
begin
at
step
00
of
program
memory
(page
78).
Executed
as
a
recorded
program
instruction:
Run/stop.
Begins
Run/stop.
Stops
execution
of
a
stored
program.
Stops
execution
if
program
is
running
(page
83).
Go
to.
Followed
by
two-digit
number,
positions
calculator
to
that
step
number
of
program
memory.
No
instructions
are
executed
(page
82).
program
execution
(page
83).
Go
to.
Followed
by
a
two-digit
number,
causes
calculator
to
execute
the
instruction
at
the
specified
step
number
next,
and
continue
program
execution
sequentially
from
there
(page
87).
PROGRAM
Mode
Active
keys:
Sing!e
step.
Displays
step
number
and
contents
of
next
program
memory
step
(page
81).
@
Back
step.
Displays
step
number
and
contents
of
previous
program
memory
step
(page
81).
Automatic
RUN
Mode
Pressed
from
keyboard:
Single
step.
Displays
step
number
and
keycode
of
current
program
memory
step
when
pressed;
executes
instruction,
displays
result,
and
moves
to
next
step
when
released
(page
92).
@
Back
step.
Displays
step
number
and
keycode
of
previous
program
memory
step
when
pressed;
displays
original
contents
of
X-register
when
released.
No
instructions
are
executed
(page
93).
Any
key.
Pressing
any
key
on
the
keyboard
stops
execution
of
a
program.
Executed
as
a
recorded
program
instruction:
Pause.
Stops
program
execution
for
1
second
and
displays
contents
of
X-register,
then
resumes
program
execution
(page
84).
Conditionals.
Each
tests
value
in
X-register
against
thatinY
-register
or
0
as
indicated.
If
true,
calculator
executes
instruction
in
next
program
memory
step.
If
false,
calculator
skips
next
step
(page
90).
No
operation.
Calculator
executes
no
operation
and
continues
program
execution
sequentially
with
the
instruction
in
the
next
program
memory
step
(page
94).
12
-
LT
8L
PRESET
-
A
FETCH
L
EXECUTE
LR
INTERRUPT
STEP
SYSTEM
EXTEND
The
HP-25
Means
Painless
Programming
Your
HP-25
is
a
versatile,handheld
electronic
calculator
that
uses
the
powerful
Hewlett-Packard
logic
system
to
compute
answers
to
complex
mathematical
problems
in
either
of
two
modes:
=
Manual
problem
solving.
You
work
step-by-step
through
the
toughest
of
problems,
choosing
from
among
the
dozens
of
functions
available
to
calculate
the
correct
answer
quickly
and
easily.
=
Programmed
problem
solving.
The
HP-25
memorizes
a
sequence
of
up
to
49
different
functions
as
you
press
them,
and
then
repeats
that
sequence
automatically
as
often
as
you
wish
to
solve
a
particular
type
of
problem.
That’s
all
there
is
to
it!
A
program
is
nothing
more
than
a
se-
quence
of
manual
keystrokes
that
is
remembered
by
the
calcu-
lator.
You
can
then
execute
the
program
as
often
as
you
like.
No
prior
computer
programming
experience
is
necessary
for
HP-25
calculator
programming.
To
see
the
close
relationship
between
the
manual
solution
to
a
problem
and
a
programmed
solution,
let’s
solve
a
problem
manually,
and
then
use
a
program
to
solve
the
same
problem
and
others
like
it.
Manual
Problem
Solving
To
calculate
the
surface
area of
a
sphere,
the
formula
4
=
7
d*
can
be
used,where:
4
is
the
surface
area,s
is
the
value
of
pi,
3.1415...,
and
d
is
the
diameter
of
the
sphere.
Ganymede,
one
of
Jupiter’s
12
moons,
has
a
diameter
of
3200
miles.
To
use
the
HP-25
to
manually
compute
the
area
of
Ganymede,
you
can
press
the
following
keys
in
order:
First,
slide
the
calculator
o
EE[[ov
switch
to
ON,
and
slide
the
rrem
mfl]flfl]
an
SWitch
to
RUN.
Then
press
Display
Diameter
of
Ganymede.
=
10240000.00)
Square
of
the
diameter.
9
)
4 )
=
The
quantity
.
29
32169908.78
Area
of
Ganymede
in
square
miles.
Programmed
Problem
Solving
If
you
wanted
the
surface
areas
of
each
of
Jupiter’s
12
moons,
you
could
repeat
the
above
procedure
12
times.
However,
you
might
wish
to
write
a
program
that
would
calculate
area of
a
sphere
from
its
diameter,
instead
of
pressing
all
the
keys
for
each
moon.
To
calculate
the
area
of
a
sphere
using
a
program,
you
should
first
write
the
program,
then
you
must
record
the
program
into
the
calculator,
and
finally
you
run
the
program
to
calculate
the
answer.
Writing
the
Program:
You
have
already
written
it!
A
program
is
nothing
more
than
the
series
of
keystrokes
you
would
execute
to
solve
the
same
problem
manually.
Recording
the
Program:
To
record
the
keystrokes
of
the
pro-
gram
into
the
calculator:
1.
Slide
the
PRGM-RUN
switch
eron[[[Hll*~
to
PRGM
(program).
2.
Press
to
clear
the
calculator.
3.
Press
the
following
keys
in
order.
(When
you
are
record-
ing
a
program,
the
display
gives
you
information
that
you
will
find
useful
later,
but
you
can
ignore
the
display
for
now.)
)
1
B
S
These
keys
are
the
same
keys
you
pressed
to
solve
the
problem
manually.
B
R
Running
the
Program:
Slide
the
PRGM-RUN
switch
erev
T
=~
back
to
RUN
and
press
in
order
EHIE
“rogramming
Now
all
you
have
to
do
to
calculate
the
area of
any
sphere
is
key
in
the
value
for
its
diameter
and
press
the
[EE)
(run/stop)
key.
When
you
press
[E5]
the
sequence
of
keystrokes
you
recorded
is
automatically
executed
by
the
calculator,
giving
you
the
same
answer
you
would
have
obtained
manually:
For
example,
to
calculate
the
area
of
Ganymede:
Press
Display
3200
3200.
[R5
32169908.78
Square
miles.
With
the
program
you
have
recorded,
you
can
now
calculate the
area
of
any
of
Jupiter’s
moons—in
fact,
of
any
sphere—using
its
diameter.
You
have
only
to
leave
the
calculator
in
RUN
mode
and key
in
the
diameter
of
each
sphere
that
you
wish
to
compute,
then
press
.
For
example,
to
compute
the
surface
area
of
Jupiter’s
moon
Io
with
a
diameter
of
2310
miles:
Press
Display
2310
16763852.56
Square
miles.
For
the
moons
Europa,
diameter
1950
miles,
and
Callisto,
diameter
3220
miles:
Press
Display
1950
11945906.07
Area
of
Europa
in
square
miles.
3220
32573289.27
Area
of
Callisto
in
square
miles.
Programming
the
HP-25is
that
easy!
The
calculator
remembers
a
series
of
keystrokes
and
then
executes
them
when
you
press
the
key.
The
early
portions
of
this
handbook
show
you
how
easy
it
is
to
manually
use
the
power
of
the
HP-25;
while
in
section
5,
Pro-
gramming,
you
will
find
a
complete
guide
to
HP-25
calculator
programming.
Even
if
you
have
used
other
pocket
calculators
or
programmed
large
computers,
you
will
want
to
take
a
good
look
at
this
handbook.
It
explains
the
unique
HP
logic
system
that
makes
simple
answers
out
of
complex
problems,
and
HP-25
features
that
make
programming
painless.
When
you
see
the
simple
power
of
your
HP-25,
you’ll
become
an
apostle
just
as
have
some
700,000
HP
calculator
owners
before
you.
P
L
ki
L
Section
1
Getting
Started
Your
HP-25
is
shipped
fully
assembled,
including
a
battery.
You
can
begin
using
your
calculator
immediately
by
connecting
the
cord
from
the
ac
adapter/battery
charger
to
the
calculator
and
plugging
the
charger
into
an
ac
outlet.
If
you
want
to
use
your
HP-25
on
battery
power
alone,
you
should
charge
the
bat-
tery
for 6
hours
first.
Whether
you
operate
from
battery
power
or
from
power
supplied
by
the
charger,
the
battery
must
always
be
in
the calculator.
To
begin:
=
Slide
the
PRGM-RUN
switch
rrew
Il
»v
to
RUN.
=
Slide
the
OFF-ON
switch
ol
to
ON.
Display
With
the
PRGM-RUN
switch
set
to
RUN,
the
bright
red
dis-
play
that
you
see
when
you
turn
the
calculator
ON
gives
you
two
kinds
of
information:
1.
You
see
numbers
as
you
key
them
in.
2.
You
see
all
intermediate
and
final
answers
as
they
are
calculated.
When
you
first
turn
the
calculator
ON,
the
display
is
set
to
to
show
you
that
all
zeros
are
present
there.
Keyboard
Most
keys
on
the
keyboard
perform
three
functions.
One
func-
tion
is
indicated
by
the
symbol
on
the
flat
face
of
the
key,
another
by
the
blue
symbol
on
the
slanted
key
face,
and
a
third
by
the
gold
symbol
written
above
the
key
on
the
calculator
case.
=
To
select
the
function
printed
in
blue
on
the
slanted
face
of
the
key,
first
press
the
blue
prefix
key
,
then
press
the
function key.
=
To
select
the
function
printed
on
the
flat
face
of
the
key,
press
the
key.
=
To
select
the
function
printed
in
gold
above
the
key,
first
press
the
gold
prefix
key
,
then
press
the
function
key.
13
14
Getting
Started
_To
execute
this
function,
first
“press
|,
then
press.
9
...To
place
this
number
into
the
display,
pressé.
-
To
execute
this
function,
first
press
,
then
pressé.
In
this
handbook,
the
selected
key
function
will
appear
in
the
appropriate
color
(either
gold
or
blue),
like
this:
i
Keying
in
Numbers
Key
in
numbers
by
pressing
the
number
keys
in
sequence,
just
as
though
you
were
writing
on
a
piece
of
paper.
The
decimal
point
must
be
keyed
in
if
it
is
part
of
the
number.
For
example:
Key
in
148.84
by
pressing
the
keys
Display
(1]
[a]
(-] (4]
148.84
The
resultant
number
148.84
is
seen
in
the
display.
Negative
Numbers
To
key
in
a
negative
number,
press
the
keys
for
the
number,
then
press
(B9
(change
sign).
The
number,
preceded
by
a
minus
(—)
sign,
will
appear
in
the
display.
For
example,
to
change
the
sign
of
the
number
now
in
the
display:
Press
Display
-148.84
You
can
change
the
sign
of
either
a negative
or
a
positive
num-
ber
in
the
display.
For
example,
to
change
the
sign
of
the
—148.84
now
in
the
display
back
to
positive:
Press
Display
CHS 148.84
Notice
that
only
negative
numbers
are
given
a
sign
in
the
display.
Clearing
'
.
You
can
clear
any
numbers
that
are
in
the
display
by
pressing
BE
(clear
x).
This
key
erases
the
number
in
the
display
and
replaces
it
with
0
.
Press
Display
0.00
]
If
you
make
a
mistake
while
keying
in
a
number,
clear
the
entire
number
string
by
pressing
[§%3
.
Then
key
in
the
correct
number.
Functions
In
spite
of
the
dozens
of
functions
available
on
the
HP-25
key-
board,
you
will
find
the
calculator
simple
to
operate
by
using
a
single,
all-encompassing
rule:
When
you
press
a
function
key,
the
calculator
immediately
executes
the
function
written
on
that key.
Pressing
a
function
key
causes
the
calculator
to
im-
meaiately
perrorm
that
tunction.
For
example,
to
calculate
the
square
root
of
148.84
merely:
Press
Display
148.84
o
To
square
the
result:
Press
Display
a
12.20
148.84
and
are
examples
of
one-number
function
keys;
that
is,
keys
that
execute
upon
a
single
number.
All
function
keys
in
the
HP-25
operate
upon
either
one
number
or
two
numbers
at
a
time
gexcept
for
statistics
keys
like
and
[°]
—more
about
these
ater).
Function
keys
operate
upon
either
one
number
or
two
numbers.
One-Number
Functions
To
use
any
one-number
function
key:
1.
Key
in
the
number.
2.
Press
the
function
key
(or
press
the
applicable
prefix
key,
then
the
function
key).
For
example,
to
use
the
one-number
function
&
Jkey,
you
first
key
in
the
number
represented
by
x,
then
press
the
functionkey.
To
calculate
1/4,
key
in
4
(the
x-number)
and
press
[£]]
.
Press
Display
4
&
x
0.25
Now
try
these
other
one-number
function
problems.
Remem-
ber,
first
key
in
the
number,
then
press
the
function:
1
—
75
=
/2500
=
10°
=
(Use
the
[
key.)
~/3204100
=
log
12.58925411
=
712
-
Two-Number
Functions
Two-number
functions
are
functions
that
must
have
two
num-
bers
present
in
order
for
the
operation
to
be
performed.[+]
[-]
and[+]are
examples
of
two-number
function
keys
because
you
cannot
add,
subtract,
multiply,
or
divide
unless
there
are
two
numbers
present
in
the
calculator.
Two-number
functions
work
the
same
way
as
one-number
functions—that
is,
the
operation
occurs
when
the
function
key
is
pressed.
Therefore,
both
nuum-
bers
must
be
in
the
calculator
before
the
function
key
is
pressed.
When
more
than
one
number
must
be
keyed
into
the
calculator
before
performing an
operation,
the
key
is
used
to
separate
the
two
numbers.
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