Monroe 770 User manual

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MONROE INTERNATIONAL A DIVISION OF LITTON INDUSTRIES
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MONROE rn
GENERAL OFFICES: ORANGE. NEW JERSEY
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"Copyright 1968 Mon~ InteI'nIIIcNllII -
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Payroll , •. """,.,.,.",'"""... 22
Accumulation of Items and Extensions. , :, 23
Averaging ,., •. ,' .. ,,' .. _ , •. " 23
Discount _ .. ' ' "' .... 24
Chain Discount , _ ...• o ••• , •• 24
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Mark-up ' ' , _" 24
Proration ,."", "" •. , .• ', •• ,.. 2&
Percentage Distribution '" ..•. , • o •• , o. 21
Percenlage',,-\. co''.: ~ • -.-" ~-.;. '. ~ ~ _~~ .:".<;',_'i~ __ ;i::,-o'-~~'-~-:-~i-.,:- 2~_-:-
Expense as Per cent of Sales ... 0 • 0 • 0 '0 •• 21
Group and Grand Total Addition •...•• 0 " 21-
Two-total Addition '.'" ...• _: o' 0" • 0 ,. 21
Ins'uraJice.';;-{:)k'~-'-.' _.' ~ -.' .' '. :. ~ -~ ~~--:/~-::,;,_,.:-'.:_:>~\_-~, ~ -,-30 .'. -
Simple Interest ." _ ...•.. , .• , .•••• 0 ;. 30
Bond Amortization .' .. ' .... : ' ...... , ... 31 -
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Fund Pncmg •... , . ' . _ .... :." .•.. >0 82·
oCubic Volume .. ' ..........•...• : • •• 88.
Linear Interpolation ..... , ....••..•• , .• 33
Statistical Summations .• _.' , .••••• , ~
Standard Deviation - ' .•... " •• -.. ....
Square Root,. _ - _ .. , • 0 • • • • • •• 8&·
Trend '. ~ine_.',~ :,~ -"~_,' ~ :~ _ .. ' -'-,' .<-." ~', -;-'-~-,':; .<,-_~ :~', -~ -,:.<,,:/.; ~~: -~,' 31"
ConcludIng N<;>te ...•. , ••••••.• , o' 0 •• " 31
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,CONTENTS,
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Operating ContrOls and Their Use , , , , , , , ,. 4
Your Silent Partner .,
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Fundamental Operations
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Monroe 770 Electronic Calculator , , ,', , , , " 2
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NROE INTERNATIONAL A DIVISION OF LITTON INDUSTRIES • GENERAL OFFICES: ORANO". NfW JfIlU'

MONROE rn
Your Silent Partner ...
The 770 ELECTRONIC CALCULATOR
TIris Monroe's silent efficiency is matched only by its electronic speed and operational
ease. Now you can solve arithmetic problems in milliseconds ... easily ... silently.
The 770's memory and storage registers and its advanced electronic circuitry are
designed for calculations using any combination of arithmetic operations. Every
answer is instantly available for subsequent use; every answer is automatically
displayed decimally correct.
Algebraic logic, too, has been designed into the Monroe 770. All negative entries and
results are indicated by an amber light. .' .
TIris booklet provides complete instructions for operating the Monroe 770 Electronic
Calculator
... your silent partner.}
1

MONROE
770 ELECTRONIC CALCULATOR
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OPERATING CONTROLS AND THEIR USE
TURN ON THE CALCULATOR
To turn on the Monroe 770, move the on·off slide (4) to the left so the
red dot shows.
No warm·up time is required. To turn the calculator
off, move the
sl ide to the right.
Before starting
to calculate you should make sure the arithmetic reg·
isters and display
(1) are cleared by depressing the'll and Ckeys.
DISPLAY
The display shows all entries and answers In large, illuminated
numerals.
NUMBER ENTRY
Set anumber in the 10·key keyboard (25) by depressing the keys that'
correspond to the digits in the number. For example: 406 is set by
depressing 4, then 0, then 6. The number is shown in the display.
DECIMAL KEY
Depressing the decimal key (24) locates the decimal in the keyboard
number. Touch this
key before setting the decimal part of the num·
ber.
When setting awhole number, the decimal key does not have to
be used.
DISPLAY CLEAR KEY
If anumber is set incorrectly, it can be cleared by depressing the
C key (12).
4
111111
111111
111111
. 0
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C
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OPERATING CONTROLS AND THEIR USE
BASIC ARITHMETIC
PLUS KEY
Prepares the arithmetic unit to add the next num·
ber in the display.
MINUS KEY
Prepares the arithmetic unit to subtract the next
number in the display
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ENTER MULTIPLICAND KEY
Prepares the arithmetic unit to multiply the num·
ber in the display
by the next number in the display.
ENTER DIVIDEND KEY
Prepares the arithmetic unit to divide the number
in the display by the next number in the display.
EQUALS BAR
Completes the addition, subtraction, multiplica·
tion,
or division, and transfers the answer to the
display.
ARITHMETIC REGISTER CLEAR KEY
Clears the arithmetic registers of any accumula·
tions or remainders of division problems.
ARITHMETIC REGISTER READ KEY
When held down this key displays the contents of
the arithmetic register.
When released it brings
back the number formerly in the display.5

The arithmetic group of keys performs the four basic rules of arithmetic:
addition, subtraction, multiplication, and division.
Each problem is entered
in the calculator exactly as the equation would be written on paper. The
calculations take place in the arithmetic register and, at the end of the
problem, the answer is transferred to the display register. For example:
12 +5 - is keyed into the 770 just as it is written on paper
Set 12 Depress +
Set 5Depress =
.Read 17 Answer .in display
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12 - 5 -
12 X
5-
12 : 5 =
Set 12 Depress-
Set 5Depress =
Read 7Answer in display
Set 12 Depress x
Set 5Depress =
Read 60 Answer in display
Set 12 Depress :
Set 5Depress =
Read 2.4 Answer in display
In each case the answer is displayed within asplit second.
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12 +5 - 8
OPERATING CONTROLS AND THEIR USE
Set 12 Depress +
Set 5Depress -
Set·8 Depress =
Read 9Answer in display
The answer in the display can be used for the next arith-
metic operation without resetting. For example:
(12 +5) X3Set 12 Depress +
Set 5Depress =
Read 17 Answer in display
Depress x
Set 3.......Depress =
Read 51 Answer in display
The result of 12 +5did not have to be reentered through
the keyboard. Since it is in the display. adepression of
the X
key sets up that number as amultiplicand.
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OPERATING CONTROLS AND THEIR USE
OVER CAPACITY
In acase where the product of amultiplication exceeds the 15·digit capacity,
the
770 provides for acorrect answer of up to 30 digits. Aproduct of 16 to 30
digits is shown in the following way:
The left·hand digits in excess of 15 are displayed. The right·hand 15 digits
remain in the arithmetic register and can be displayed by depressing the ~, key.
Before beginning another problem, clear the arithmetic register by depressing
the
'iI.
Example
1111111112=12345678987654321
Instructions
Set 111111111.....Depress x
Depress =
Read 12 in display
Depress and hold
It,
Read 345678987654321 in display
OVERFLOW LIGHT
The red overflow light indicates that an operation
has produced an overcapacity.
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OPERATING CONTROLS AND THEIR USE
STORAGE REGISTERS
The two storage registers can be used as memory registers as
well as accumulators.
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I II .
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II
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STORAGE PLUS KEYS
The storage plus keys add the number in the dis-
play to the selected storage register. The number
remains in the display.
STORAGE MINUS KEYS
Subtract the number in the display from the se-
lected storage register. The number remains in the
display.
STORAGE RECALL KEYS
Recall the number in the selected storage register
to the display. The number remains in the storage
register.
STORAGE RECALL·CLEAR KEYS
Recall the number in the selected storage register
to the display and clear the storage register.
STORAGE READ KEYS
When held down, the storage read keys display the
contents of the selected storage register. When re-
leased, the number formerly in the display returns.
STORAGE LIGHTS
The green storage lights Iand II indicate when their
respective storage registers are in use. 9

OPERATING CONTROLS AND THEIR USE
MEMORY REGISTER
MEMORY-IN KEY
MPuts the number in the display into the memory
register. Only the absolute value is retained in
the
memory; the algebraic sign is always positive. The
number with its propersign stays in the display and
can be used immediately for further calculations.
MEMORY RECALL KEY
Recalls the memory amount to the display; the
number
is retained in the memory register.
ROUNDOFF
SHIFT-ROUNDOFF KEY
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This key allows the operator to have control over
the number of digits in the answers and provides
for roundoff of results.
Each depression of this key
shifts the number in the display
one place to the
right, dropping the right·hand digit.·
If the digit
dropped was 5 or more the next digit is increased
by
1. If the digit dropped was 4 or less, the next
digit remains the same. See instructions for half-
cent roundoff.

OPERATING CONTROLS AND THEIR USE
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NEGATIVE VALUES
With the exception of the memory register, the 770 follows
the rules governing algebraic sign in all cases, Anegative
number is entered by depressing
the -key before setting
the number. For example:
12 X -6
-72 Set 12.....Depress x
Depress -
Set 6.......Depress =
Read -72 Product in display
Anegative total recalled from storage retains its negative
sign and affects the calculations accordingly.
When avalue is placed in the memory register, it loses its
algebraic sign
and retains only its absolute value.
NEGATIVE LIGHT
Anegative product is identified by the amber negative light.
11

MONROE rn
MONROE INTERNATIONAL A DIVISION OF LITTON INDUSTRIES • GENERAL OFFICES: ORANGE. NEW JERSEY
FUNDAMENTAL OPERATIONS
The next few pages give step-by-step instructions for
addition,
subtraction, multiplication, and division. Ac-
tually the arithmetic operations could almost be self-
taught. All the operator has to know are the arithmetic
symbols learned in elementary schooL
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When adding acolumn of numbers it
is usually best to add in aStorage
Register.
Example
130.46
12.55
81.81
3,541.00
3,765.82
97.23
6.00
3,869.05
The same addition problem can be
done
in the Arithmetic Register.
ADDITION
Instructions
Depress
~
Set 13p.46 .....Depress 'Ii
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Set 12,.55 Depress'li
Set 8~ .81.. Depress 'Ii
Set 3541.. Depress"li
Depress ~
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Read 3765.82 Sub·total in display
Set
97.23 Depress 'Ii
Set 6Depress 'Ii
Depress ~
Read 3869.05 Total in display'
Instructions
Set
130.46 Depress +
Set 12.55 Depress +
Set 81.81.. Depress +
Set 3541.. Depress =
Read 3765.82 Sub·total in display
Depress +
Set 97.23 Depress +
Set 6Depress =
Read 3869.05 Total in display
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SUBTRACTION
Storage Register
884.15
-90.33
793.82
When atotal is negative the true neg·
ative
number will be displayed and
the amber minus light will come on.
Example
536.1
-645.0
-108.9
.Depress ~
Set 884. 15 Depress 'Ii
Set 90.33 Depress ".
Depress ~
Read 793.82 Answer in display
./l.rithmetic Register
Set 884. 15 Depress -
Set
90.33 Depress =
Read 793.82 Answer in display
Instructions
Storage Register
Depress ~
Set 536.1.. Depress 'Ii
Set 645 Depress".
Depress ~
Read -108.9 Answer in display
ArithmeTic,Register
Set 536. 1.. Depress -
Set
645 Depress =
Read -108.9 Answer in display
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MIXED ADDITION AND SUBTRACTION
Depress 1:-
787
125
-231
29
710
23x3=69
Set 787 Depress 'Ii
Set 125 Depress 'Ii
Set 231.. Depress ii
Set 29 Depress 'Ii
Depress 1:-
Read 710 Total in display
Set 787 Depress +
Set 125 Depress -
Set
231.. Depress +
Set 29 Depress =
Read 710 Total in display
MUL TIPLICATION
Set 23 Depress x
Set 3Depress =
Read 69 Product in display
28'/2 hrs. @$3.62 per hour =$103.17
Set 28.5 Depress x
Set
3.62 Depress =
Read 103.17 Answer in display
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Multiplication with Addition of Products
Instructions
Depress
~
Example
12 X 5 = 60
440 X7= 3080
11 X 42 = 462
3602
Set 12 Depress X
Set 5Depress =
Read 60 Product in display
Depress
"Ii
Set 440 Depress x
Set 7Depress =
Read 3080 Product in display
Depress
"Ii
Set 11.. Depress x
Set 42 Depress =
Read 462 Product in display
Depress
"Ii
Depress ~
Read 3602 Total in display
Multiplication with Subtraction of Products
Instructions
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Example
175 X 16 = 2800
-(39 X21) = -819
1981
Depress ~
Set 175 Depress x
Set 16 Depress =
Read 2800 Product in display
Depress
"Ii
Set 39 Depress x
Set 21.. Depress =
Read 819 Product in display
Depress
Ii
Depress ~
Read 1981 Total in display

MUltiplying a Series of Numbers
25 X 35 X 45 = 39,375
Set 25 Depress x
Set 35 Depress =
Depress x
Set 45.....Depress =
Read 39375 Answer in display
Multiplication by the Same Number
124 X 31.82 = 3.945.68
. 124 X 5.60 = 694.40
124 X 40.07 = 4.968.68
122= 144
Set 124 Depress x
Set
31.82 Depress =
Read 3945.68 Product in display
Set
5.6 .........Depress =
Read 694.4 Product in display
Set
40.07 .....Depress =
Read 4968.68 Product in display
SQUARING
Set 12.....Depress x
Depress =
Read 144 Product in display
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Example
525..;- 7= 75
DIVISION
Instructions
Set
525 ,.Depress :
Set 7Depress =
Read 75 Quotient in display
Division Stop Procedure
As in any desk calculator adivisor of zero will cause the system to run
continuously.
If this illogical operation should occur, the procedure to
correct it is as follows:
Depress ;::;
Depress C
Begin problem again.
Division By the Same Number
Instructions
Example
4589.25 ..;- 436.58 =10.51
1952.54
..;- 436.58 = 4.47
Set 4589.25 Depress :
Set
436.58 Depress M
Depress =
Read 10.51 Quotient in display
Set
1952. 54.....Depress :
Depress
~
Depress =
Read 4.47 Quotient in display
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